Ruling question on exposed cards and premature Turn

[pipster]

This is in a local live game (not in a casino) and I had to rule on it. I will post my ruling after I get some feedback.

4 players in the hand. SB, BB, MP, CO

After the pre-flop betting the flop is revealed, SB, BB, MP all check. CO bets 2K into a 3K pot.

SB and BB after some ooohhing and ahhhing fold. BB happened to be dealing and asked CO what he has. CO flips up his cards exposing 10/9 of clubs for top pair, and the flush draw.

BB then proceeds to deal the turn and the river "just to see what happened". However, MP had not bet or folded yet.

So now there is CO with his hand exposed and a 2K uncalled bet out there. MP with his hand still visibly in front of him, and had not yet called the bet. The turn and river already dealt, before MP had called or folded the Flop bet.

What is your ruling?