No, I think the equivalent would be pointing my loaded rifle into a car with occupants in it. I understand your point about apples and oranges, but for me it is a fundamental, and I would choose to live in a society where that is a red line.
My pal was in the Welsh Cavalry (Queen’s Dragoon Guards) as sniper specialist in Iraq and Afghanistan. Following return he was with Essex Police. He has not had the same level of close-up interaction you have had, and I am quoting him third party versus your first hand experience, but to bring this back to the OP there is (and should be) a very different approach in military SOP in a war zone versus civilian (police) SOP in a rural setting. If as an armed officer you suddenly see every call out as dealing with an enemy combatant, rather than policing through consent, then we need a fundamental restructuring of police culture.
If he was QDG I doubt his numbers are dissimilar to mine - it doesn’t take long when you’re on the streets interacting with locals constantly. He probably just hasn’t sat and done the finger maths.
We can agree to disagree about what is hypothetically or morally right; but the fundamental point remains that in practice, and whether you like it or not, physically pointing a firearm at someone is not, in policing or military training, seen as the massive rubicon it is in sporting shooting. Pointing a firearm at someone is done frequently in the military, and slightly less frequently in the Police. The rubicon line in both those contexts is actually shooting people, and covering a potential threat with a pointed firearm is in many scenarios seen as the right thing to do. Policing by consent doesn’t mean saying ‘please’ in every encounter.
So what? As shooters we need to bear in mind that if an ARV gets called on you they will perceive you, to some degree, as a threat. To what extent they regard you as a threat will depend on their individual experience and knowledge, and to a very large extent what was said on the phone (and potentially what else is going on around as per the Chequers comments above). When they turn up and you are in fact holding a firearm, it is possible they’ll point their firearms at you until everyone has figured out what is going on. Remember that as you also have a firearm you have parity with them, in terms of violent potential, so they will be seeking to ensure their safety. I imagine it is also incredibly rare for an ARV to attend an incident and find that there actually IS a firearm there, the police officer in question may well be seeing a 'civilian' with a gun in their hands for the first time. Take Uncle Jules' advice and 'Be cool'
Regards describing the UK police as seeing the public as enemy combatants in war zones....that is hyperbole akin to describing stalking as 'People torturing deer to death'. In war zones enemy combatants can (and are) shot on sight - the police did not turn up and shoot the OP, high five, then leave. To stave off the inevitable, neither Iraq (post invasion) nor Afghanistan were war zones, and neither the various militias in Iraq nor the Taliban were legally defined enemy combatants, in legal terms both were, broadly speaking, high risk policing actions. Eastern Ukraine is a 'war zone'- there's plenty of footage online if you want to establish how such things are handled in war.
Surely a rifle slung on a shoulder, carried in one hand is a low threat that doesn't need an gun aimed at the first interaction. It's not like there is a risk from a bomb vest. A low ready will still be quick enough without being so confrontational from the get go.
Going by some of the logic here, why not greet all members of the public with Tazer / PAVA drawn, just in case?
I've skated over a bit of complexity in my perspective here to challenge the assertion that the police and military should NEVER point a weapon at anyone unless they have already decided to shoot them, and that any police officer or soldier who does so is an 'idiot' and 'ill trained'. My point is that in general terms pointing weapons at people is something that the police and military do an awful lot, that it is taught to them as an appropriate part of their tool kit, and that if you are stopped by an ARV when out shooting you should recognise that it is a possibility it will happen to you. (and that if it does it probably doesn't represent an egregious miss-step by the police)
In terms of this specific incident, I personally would agree with you that pointing a weapon is on the face of it, OTT in this incident (Although we don't know how pointed it was, generally at the OPs knees, or shoved into his face?), but I would characterise it as being towards one end of a spectrum of understandable responses rather than outrageously inappropriate. We don't know very much about the Police Officers perspective on the incident going in - what were they told by the control room? What were there expectations? What was there level of experience? The OP described them as 'polite' though, so I doubt they were too assertive with him.
More broadly, I was driving at what looks to me like a hypocrisy. As sporting shooters we frequently complain that 'urban folk' (or whomever) do not understand shooting, stalking or our use of firearms in our context and seek to impose their perspectives and rules on us. Plenty of people on here have been doing exactly the same thing to 'tactical' firearms users such as the police and military. Their use of firearms, the risks they have to take and what is appropriate behaviour is different to a sporting context, and shouldn't be judged on sporting criteria any more than stalking should be judged by central London criteria.