Wellll.... yes and no, depending on what you mean by disregard it.
He affirmed its finding already. And even if he didn’t, he can’t change doctrine. I guess he could try to establish canon law in contradiction to that doctrine, but then the bishops all have their own apostolic authority. All hell would break loose (literally), and all he would accomplish is the diminution of his own authority and lots of confusion. If he tried to issue a heretical doctrinal statement, he’d probably be declared an antipope. That’s if he wasn’t struck dead by divine intervention first. (Don’t laugh; it’s happened.)
And Obama can't unilaterally change the Constitution, either, but there is no need to do so when ignoring the law accomplishes the same goal.