The welterweight unification is scheduled for May 2 at MGM Grand here.
Roach made the comments in a telephone interview Wednesday from Pacquiao’s training camp in Hollywood, Calif.
“I would ask him to quit because there’s nothing else out there,” Roach, Pacquiao’s longtime trainer, said. “I think it would be a great way to retire and I think would be a great way to help Manny try to become president of his country, because I think he’s getting close to that next year.
“I think he enjoys that, he likes helping people, and he wants to make his home a better place. He really does. So I kind of like that for him.”
Pacquiao is the lone congressman from the province of Sarangani in the Philippines, and widely is considered a strong future candidate for the national presidency.
Mayweather (47-0, 26 KOs) has said he plans to fulfill his CBS/Showtime contract, which expires after two fights this year, then retire.
Roach said he wouldn’t be surprised if Mayweather considered retiring one fight earlier should the Grand Rapids native defeat Pacquiao (57-5-2, 38 KOs).
“Win or lose, it wouldn’t be a bad move for anybody at this point, because really, who do we have to fight after this one? Nobody cares what’s next,” Roach said.
Pacquiao is in the tapering process late in camp. Roach said Pacquiao would spar twice more, six rounds today and four Saturday.
He said Pacquiao is “still going through a lot of sparring partners” but acknowledged the fighter isn’t the same dynamo he was a few years ago.
Pacquiao has not stopped an opponent since his scintillating 12th-round finish against Miguel Cotto in 2009.
After the fighter became a Christian in late 2011 — around the time of his third fight with Juan Manuel Marquez, and at a time his marriage was in danger of failing — Roach said Pacquiao might have made a conscious decision not to risk injuring opponents.
“He told me when he went into the new religion, and he’s a born-again Christian now, he told me, ‘I don’t have to hurt my opponent, I just have to beat him,'” Roach recalled. “And I said, ‘Well, if you knock the guy out a round before he knocks you out, you won’t have to worry about that so much.’
“So I don’t agree with him completely. But the thing is, it’s the way he is now. I think he’s done a lot of good things with his life since the religion. But I think one thing we did lose was a little bit of his killer instinct.”
Roach noted that Pacquiao did score six knockdowns in his most recent fight, against Chris Algieri, and that he thinks instinct would take control if Mayweather is hurt.
“Because it’s such a big, big fight, if somebody gets hurt in this fight, I know the other guy’s going to try to knock him out,” Roach said. “It’s their job.”