In order for them to do that, it'd have to be allowed for them to do that.
If they saw him hit Walt first they could call it on the replay. I believe officials have discretion for calling technicals for misconduct and provoking.
Did he hit Walt?
He had Walt's arm, but it didn't look like he was provoking anything. That kind of hold happens quite often during a game, I'd suspect.
And that kind of hold happening all the time is why I believe college officials are terrible
That doesn't change the fact that they can't call him for it looking at the replay.