This interaction is the equivalent of having your car impounded because you did 56 in a 55.
Did the old, confused/frail man do something wrong by "touching" a LEO? YES
Did the young, strong LEO do something wrong by almost killing him over that touch? YES
Is the second "wrong" (especially in light of the responsibility and training a LEO should have) a justifiable response? NO
Should that LEO lose his job and be held responsible for his actions? YES
If this isn't a perfect example of excessive force, I don't know what is...
Did the old, confused/frail man do something wrong by "touching" a LEO? YES
Did the young, strong LEO do something wrong by almost killing him over that touch? YES
Is the second "wrong" (especially in light of the responsibility and training a LEO should have) a justifiable response? NO
Should that LEO lose his job and be held responsible for his actions? YES
If this isn't a perfect example of excessive force, I don't know what is...