Yea it's bull shit but that's the way it is some places.
Some of the cops in my classes say it has gotten so bad with the tazer it's almost useless to carry it.
The same with an asp, you can not hit to the head or any joint. It is very restricted where you can hit.
I'm a Border Patrol agent and I can confirm what you said about the tazer--we actually had a mandatory training a few months back detailing pretty much what you said--if you deploy the tazer, and they fall down and hit their head on the pavement and die (which has happened), the courts will view it as lethal force and the officer will need to explain why he felt the crime was serious enough that it was worth the suspect's life. Officer intent doesn't matter, only the result.
Needless to say, we all kinda looked at each other like "WTF" and a lot of guys stopped carrying the tazer altogether.
Same goes for other less-lethal weapons, of course.
It's interesting, though, because cops (such as Darren Wilson) have repeatedly been cleared of wrongdoing for shooting unarmed attackers.
So essentially, the court is telling officers to use lethal force instead of less-lethal force.