If he watched the show last season, he saw 2 important things:
1. When it was women vs. men, women never lost.
2. When a team with women lost, the women turned on themselves, not the men, and took each other out.
So, he volunteers to be the guy who switches teams and becomes the PM for the women. Okay, so now it's very likely that he gets a win as PM b/c of the women vs. men thing (and they do win). This also gives him exemption for next week. Even if the team lost or loses in the next few weeks, the women are likely to turn on themselves, not him. Smart move overall, I think.
Conversely, I thik it was a dumb move by Pamela to join the guy's team, which I think she found out last night.