It certainly is stupid, it's obvious enough that they realized the attempts at preventing her participation in the competition, but..
Not bringing up the guy as the main suspect despite that deal being rather recent and knowing he really doesn't want her to win,
along with knowing he's enough of a bigshot to have/use enough people to do those things.
(ESPECIALLY when the others folded and just started sabotaging them too, that was a dead giveaway.)
At this rate, next one of them need to be taught you shouldn't try breathe below the watersurface if you want to avoid getting water inside your lungs. -.-
Hope this arc is over soon since their stupidity is unusually annoying in it, though with the current pacing it seems quite possible this could get dragged on for some time.