Cannot taze - too dangerous - he could be on you with that knife in a second.
Bean bag shotgun would have been a good choice. They probably don’t have them. Non-lethal shotgun rounds would have been great. Are they not issued?
Could have hit him with a car. But you would be sued into oblivion. Not allowed.
Since they were not being attacked they could have shot him in the legs. Potentially fatal but less likely so. At that range, even though he was bouncing around, one could easily make a few hits.
But, that isn’t how they are trained.
All that said - maybe they thought he had a handgun. Puts a completely different light on the incident.
You sound like quite an expert on this kind of thing. Perhaps you should join the force and show them how it is done.
why not stun guns...why not bean bags?....why not throw a lasso around him like they did in the old days?....