First, vs a variance donk like Yoss, I actually prefer a check on the turn a good % of the time, as from what little I know about him, he is fully capable of CR'ing a full range of hands here, from air to pair+FD, trips, and FH. If we check, we hate a spade of course, but he will bet many rivers and we can call most easily. While the turn MAY still be a fairly standard CR call, depending on the CR size, Yoss will also hammer many rivers, and I think that makes it -EV. Vs the minCR in particular, I have seen more than a few hands where he minraises big hands, then pounds after. If this is the case, the immediate odds of 4.4-1 are just enough if we put him dead on a flush, ( 3 9's, 3 K's, 3 A's, 1 deuce). But the problem with that is:


A: If we DO hit, is he going to bet a flush into a 2 pair board? I don't know quite how crazy he is, but I'm thinking maybe not THAT crazy. Also, our hit can hit him harder if he has A 9x or Kx, ( which I think is unlikely with minCR)
B: We could actually be drawing near dead. Yoss seems to bag big hands preflop much more than most, so KK and 99 cannot be ruled out, and A 2x would suck balls too.

In summation, betting turn puts us in a crappy spot vs an unpredictable player, and makes for a very hard decision on the river unless an ace or 2 hits.

Check turn, fold to minraise. For a nit like my friend, building big pots with guys like Yoss with marginal hands is a bad idea. Nits are better off rope-a-doping these types.