This hand came up last night and although I wanted to get greedy and keep the third player in the pot, the risk manager in my head said it was better to isolate. I may have given up a lot of money though, I'm not sure. What play would you make?

Stack sizes are roughly:
Me $900
Player 2 $450
Player 3 $240
Player 4 $1200

From one off the button I get [Kc] and make it $20
I get three callers. Pot is roughly $85

Flop is [Th][6h]

Player 2 checks
Player 3 goes all-in for $240
Player 4 thinks and calls the $240
I push all-in for $880 more to isolate on Player 3
Player 2 folds
Player 4 thinks for a while and says he might be drawing dead and folds.

Player 3 turns over [Js]

Turn and river are bricks and I rake in a nice pot.

Here's the question though, player 4 is pretty invested in this pot, if I can put him on a heart draw that hits I can make a lot more on the hand. If he has a baby flush already, a straight draw or lucked into a KT two pair then my all-in has a good chance to get him to fold letting me isolate on player 3 who, barring a flopped set, I probably have beat.

What do you make of the first all-in call by player 4? He never did show his cards or let on what he had. He was a bit of a risk taker, but not overly reckless. I desperately wanted to put him on the flush draw and just call also, but in the end I couldn't do it and made the push to get him out. Good thought process or am I missing something?

Just push, if you call your draw is about as obvious as humanly possible. If the heart comes off its hard to see this deep stack giving you the rest of his money with the . Unless they have the nut flush(which he cant have) people aren't likely to just smooth call with a flush here. There is a good chance that this caller in the middle has outs against you either a gutty or a 2 pair draw with his , get him out of the pot and protect your hand.