[SoftcoreRevolt]

I think you are overvaluing your 6s a bit much, especially with a donkish Button. Maybe subtract 1 out from it for the times he'll make a straight when you make two pair. Yeah its unlikely in 6 max with 3 people in, but you need to discount an out or so here with such draws (low back door flush, two pair which makes 4 to a straight, etc.)

I'm torn on if I 3 bet here or not. UTG being an unknown makes this more difficult, since we don't know if he has a tendency to overplay his overcards short handed. I'm almost tempted to donk bet him on a safe turn or a spade turn, and then do the same if we hit our draw on the river if he raises the turn.