As a good-guy, if you suggest two random people that aren't you for a mission, there's a 60% chance that you've put exactly one bad-guy on the mission, which is the worst thing possible. Especially considering that I can't think of a reason a bad-guy would ever pass a quest, since we have three of them and no plot cards.
There's a 20% chance you found two good-guys.
There's a 20% chance you found two bad-guys, which is kind of nice, but exactly one fail is still possible; so this is not a 20% chance of success.
Also, you give up any opportunity you had as leader to learn something from the outcome of the mission by being on it.
If you suggest yourself and someone else for a mission, you have a 50% chance of a guaranteed pass, and that other 50% is way better. Either we get a pass in, or you yourself know who one of the bad-guys is.
This not-so-bad 50% chance is way better than the much-worse (>60%) chance. More than likely, PPS knows this and has some knowledge the rest of us don't, which might make this a much better move than it appears, at least for his team.
HOWEVER
If you are not on this mission, and you are a good-guy, it seems pretty obvious that the odds of anything good happening on this mission are slim. If people not on this mission vote yes for it, I can only assume cast suspicion on them for doing so. Especially if the mission ends up failing.
(sort of ninja'd, but oh well)