[Willd]

Surely a non-nut flopped flush needs to protect his hand here, especially after CO called my pot sized lead on the flop - it is quite possible that CO has AdX (it's possible I could have it from his POV) so he certainly needs to protect his hand.

Also a set has the same motivation for raising. Calling with QQQ here would be a big mistake as you're allowing any flush draws a cheap chance to draw out on you (although I think 66 is more likely than QQ because of the lack of a reraise preflop)