Per a league source, referee Pete Morelli or any member of his crew could have flagged Bryant for unsportsmanlike conduct. The NFL doesn’t condone players coming that far onto the field to argue a call. However, it appears that, in the heat of the moment, a little leeway (or more than a little leeway) was provided to the Cowboys’ bench.
Also, Bryant came onto the field while the officials were in the process of trying to figure out whether a foul had or hadn’t occurred. That was the primary concern. Still, Bryant shouldn’t have entered the field of play.
It’ll be interesting to see whether the league office fines Bryant for the infraction. To fine him would be to admit that he should have been penalized, and not that he simply could have been penalized through the exercise of discretion by the officials.