> Like I said, I don't know the details of the UK incident yet and nobody does, so I was speaking generally.

That said, you are you really just fine with cops shooting people because they could have a suicide vest or they could have another gun? The police could shoot you for pulling you over for a speeding ticket because you could have a gun and want to shoot the cop to avoid your $140 fine.

The police should never act on perceived danger unless that perceived danger is confirmed.

Besides your argument is a bit stupid because it's trivially easy to rig a suicide vest to explode once a finger is removed from the explosive trigger. Killing the person just sets the bomb off. If that were a true concern the best course of action is to immediately contain the suspect and evacuate the area.