Yeah, he did get roughed up but Horn is a guy that said he could fight at 154 without an issue. Horn's size, durability and grit saw him through that one in a fight most believed he shouldn't have won on the cards. He made it a competitive fight and had far more reach, height and size than Pac. At 140 I believe Pac could still be formidable. He would beat the brakes off Lipinets (who's still largely a prospect) and some of the other top guys there. Pac is the A-side here but since Loma & Pac are both with Top Rank the only thing he'd have going for him there would be the payday in that regard. What Arum did to Pac with Horn was wrong. Pac felt he was setup and I believe that he was. Still, that was at Welterweight.
If Pac wins then I agree it wouldn't be good for the future of the sport. He's too old now and doesn't have much left. That and his political stuff is in the way of his boxing career. He wanted to fight McGregor last I heard. McGregor wants that fight in the Spring. That's a fight I wouldn't want to see. Against Loma, Pac would risk being outboxed and potentially look bad, or, he could land his left hand and potentially change that with one punch. Pac did almost finish Horn in the 10th round IIRC, so, the element of danger is still there despite him being a shell of his former self. Pac won't quit if things aren't going his way and he still can take a punch from much larger guys than Loma. His speed has diminished, his reflexes too, but his power, work rate and durability is still enough to potentially trouble Loma. That's just how I see it.