Why should he retire? He beat the undisputed champ in most people's eyes. He should either rematch or go for undisputed at 130 as that is his dream. If I was Loma I would avoid Tank at all costs, not saying he can't beat him, but he could get badly hurt and beating Tank doesn't achieve his goal.
He just basically for all intents and purposes beat the undisputed champion of his division. While I think he would have trouble with one specific person in his division, he definitely showed he's not quite finished yet (which I admit I thought he was). And if he dropped to 130, ain't no one touching him.
As others have said he can either rematch Haney or clean out 130 and go for undisputed in that division, which I think he's truly capable of doing.
Loma already tried to unify 130 and failed because no other champ would get into the ring with him. I doubt he has any more luck now.
Loma can make 126 without much of a problem. That weight suits Loma much better than 135 suits Haney. Inoue may go up to 126. That's how that fight is possible.
Davis is short and has short arms. He is closer to Loma in terms of size. He is tailor made for Loma.