My dad had dementia and have worked with dementia patients and you can indeed use your words, most of the time you change the subject/distract them.
You work with them and know their history, their family, their past hobbies- you have a connection and normally know what to say to get them out of that aggressive mood.
Sometimes not enough training is done or the right people in that setting. I think calling the police was the biggest mistake as it obviously made him more aggressive as the police can be quite intimidating, especially if your confused.
I'm sure whatever unfolded that day will come out as the body cam is being reviewed.
For the police they need an IQ test, I cant comprehend how anyone thought it was reasonable to use pepper spray, baton and taser on a elderly dementia resident.
For the care home they need to look at more training for staff to defuse situations, how this vulnerable resident got hold of a knife and better risk assessments for those with aggressive mood swings.