I'm normally pro police but that is just awful. There was absolutely no need for that level of force.
He could have hurt himself or someone else with the knife, yes it was a butter knife but pushed into an eye, or the mouth could have caused an injury beyond minor, and care workers aren't allowed to just grab him and wrestle it off him as is being suggested, it's assault.
He couldn't be left alone with it as a) he could have injured himself and b) in a place that specialises in dementia care, residents wander, it's quite often part of the condition and to prevent that can cause distress in itself, so another resident could have wandered into his room and been injured. Leaving him with it alone is failing in the duty of care.
And sometimes it's just not possible to talk someone down, especially an elderly person with a UTI, because they are not seeing the situation rationally and are unlikely to respond to rational ideas and conversation.
So yes, I do think the police needed to be called because the care workers don't have the training or permission to just wrestle the knife away from him. What followed was massively heavy handed and uncalled for. The police could have physically restrained him as much as needed to remove the knife and no more. It may have left bruises and probably would have hurt, and they'd have had to explain their actions, but charging in with a pepper spray and a taser? Massive over reaction.
I've called the police in similar situations and I have to say they've been great, they've listened to us, and I've even 'pretended' to be arrested before so that the person trusts the police officer enough to give up their weapon (and it's been forks, part of a broken cup and a drawer front!) they've walked in and from the off 'played in' to the reality of the person, made them feel they're on their side and gained trust and they're there to right the 'wrong' that's been done to the person posing the threat.
As I said I'm normally pro police but these two got it very wrong, had I been a member of staff there I wouldn't have stood by and said nothing, I'd have been trying to reason with them and explain to them and would have been appalled to witness that.
I've had to advocate for dementia patients in hospitals (to medical staff!!) who got heavy handed and entered into a battle of wills with someone who is ill or injured, needs treatment, but is also not seeing the situation rationally. Shouting instructions at someone in that state is going to get you nowhere. Trying to reason with them gets you nowhere, you need to play into their reality and gain their trust in that moment.
I'm absolutely disgusted by that video and I hope they're prosecuted.