This is from the rule book"

Article 8(f) states in pertinent part:

"If a player uses any part of his helmet (including the top/crown and forehead/”hairline” parts) or facemask to butt, spear, or ram an opponent violently or unnecessarily. Although such violent or unnecessary use of the helmet and facemask is impermissible against any opponent, game officials will give special attention in administering this rule to protecting those players who are in virtually defenseless postures . . ." (Emphasis added.)

The ref could have penalized the SEA player for spearing/unnecessary roughness. That penalty can occur during a play.