As long as it's not high - which was established in the original post - then I don't have a problem with it. I'm all in support of taking the head-hunting out of the sport, but simply peeling back and crushing someone in the mid-section is something that is the root of football. What's the alternative? To set a pick and take the brunt of the force, potentially risking personal injury? Or should the blocker just move out of the way and let the defender make the tackle?
As for the concept of someone trying to "punish," I'm just not sure how that can possibly be determined. Is it "punishing" because the blocker is faster or stronger? Or has a good angle? Or perhaps the potential tackler is just uncoordinated or unaware?
All good questions. I don't have any problem with trying to eliminate "unnecessary" or "excessive" contacts as being in the interest of the game. Viewing this clip, I have absolutely no idea what the tackler could see, or couldn't see, nor can I tell what the blocker actually saw to determine what his options were, or whether he "somewhat" held-up and refrained from "punishing" the defender.
The Umpire seemed to be in pretty good position, considering the action the play was following, but since the contact happened moving away from him, may not have been able to see those things either. There doesn't seem (as best I can see from this grainy film) any overt attempt to excessively "punish" the defender, although there is likely some instinctive effort to protect the runner.
Have we reached a point where we should EXPECT a blocker to ignore a viable threat to avoid reasonable contact? We can only respond to what we actually see and determine if it violates what we understand is prohibited. Unlike various levels of spectators, observers and reviewers we are not granted the luxury of guessing or deciding other than instantly, in real time, which is unlikely to change anytime soon.