I don't see why I'd give him credit for a better flush. The article doesn't say that he's prone to betting flush draws on the turn OOP in a multiway pot. He must have at least had something on the turn. So I most likely interpret his turn bet and subsequent river shove as 5 :heart:6
(made straight on the turn + flush draw), or a ten-high flush. In the case of the latter, maybe he was planning a check-raise on the flop with top pair (peculiar move I know, but I think it is consistent with our reads on him), but no one bets the flop so he bets the turn when he picks up a flush draw along with his top pair.
As for why he would come over the top on the river with a ten or six-high flush, well, it is very possible that he decided that this is a good spot for him to double up or nothing, since the size of the pot when you reraise is 7,200. And if he just calls and loses he will be crippled anyway with only 4,000 chips remaining... which brings us to the next point...
Are you sure that you have to call 7,000 on the river? Doesn't the phrase "all-in for 7,000" mean that he has 7,000 remaining after his initial river bet, making it 4,100 to call? Anyway, even if it's really 7,000 we have to call, I just can't see myself folding in this spot. If I lose I'm still 3,000 chips above the yellow zone, so it's not a complete disaster.