Yes, he definitely deserved to be suspended because even though it was the slightest little push tiniest of a push, Richards was in the exact position and leaning the exact way that i little tiny pushed would forced his momentum into the boards.
That said, ten games he should have gotten for stupidity, but this is a pretty clear case of carelessness, and not a case of "intent to injure" unless kaleta is a physicist, he did not realize how devistating that little push could have been. He should have realized however, that 4-5 feet away from the board is a danger area to hit any unsuspecting player from behind.
weird though, in the slo-mo, it almost looked like he was on his way to really crush him, but actually let up a little bit, and instead just decided to give him a shove to let him know that he was there, and that shove ended up being worse then if he would have drilled him.
Strange play, nothing that even is close to this should be allowed in the NHL, and if Shanahan really wants it out of the game, he would have done something (even just a fine) about the other hit in the game too. Both were hits from behind.
BOTH hits should have been punished, and any fan should see this. Glad that Richards and Ennis are both OK, both are exciting players to watch.