In this case, the decision appears to have been made without or prior to any proper investigation. What is different here is that the decision to revoke has been made... in secret.
Again, this appears not to have happened.
That's because that's what the police like putting into the media. They can't complain when it works both ways.
There's no good reason at all why they couldn't simply have written him a letter and asked him to surrender his guns at the police station. Turning up with armed policemen inside a family house (I'm unclear whether there was or wasn't a warrant) without any specific intelligence to justify doing that, is surely both unnecessary, unreasonable and wrong. We're constantly told the police are under-resourced. Apparently they're over-resourced.
If there is an enquiry, That stage appears to have been dispensed with.