While yes it could have been flagged for unsportsmanlike, forcing another kneeldown, what ref is going to bother with that?
Yes, it is deserving of the "wise man moment" public shaming with the team. Yet, except as a reminder that do that on a 4th down kneel-down and you are giving the opponent a play, that will and should be the end of it.
Now, if this was an in-conference game, then it could lead to the conference forcing the team to suspend the player for all or part of the next game; fortunately that is one of the advantages to being an independent.