It was wrong. Those officers know when you push an older man, he is liable to fall. And the police should have had liability. They had no need to do that, especially with no one around. If anything was done, they should have grabbed him, and forcibly moved him out of the way, while holding him up. I find it interesting that they were up for felony assault, not a misdemeanor assault. That would've opened up a whole new can of worms as far as liability goes. But maybe it needed to be opened for their practices with non threatening older protesters and how to handle it.
They should have know what shoving an older man could lead to, and that their actions did not take into account his lack of threat, and his age. I would hope their suspension was without pay at least for a short period, in order that they somehow suffered over the incident enough to wake them up. I would hate it that this officers attitude over the whole thing isn't simply, cool yeah no liability, no need to change my actions the next time around.
The issue wasn't just that the man lost his balance and fell, it was also how he reacted to the fall. Your reaction time and ability to mitigate your fall with quick actions to keep yourself from hitting your head is affected too. My father fell many times in his latter years, and my neighbor fell recently and had to go to the hospital for 5 days and is now in rehab. I have had to attend to her because of her fall through this whole incident, and take care of her and her invalid husband due to this. I have had head trauma like him as well, and likely suffered worse than him from the head trauma, due to non treatment for 15 hours. So this type of situation has been on my mind lately, and bothers me more than the average joe, due to my experiences. I payed attention to it from multiple perspectives when it happened because I know the dangers of head trauma first hand.
The whole group of officers didn't even slow their pace to deal with the man standing in their way. The man has a right to protest, and did not seem to do it in a non-verbal threatening way. We did not hear his verbal discussion, but that didn't even appear to be threatening in any real fashion. He didn't seem to raise his voice from the cues in the video, though we cannot truly know that from the video.