i think I would reshove here.  If he is loose, he probably opens a lot of his buttons, and will be calling a very small percentage of 3-bet shoves here.  He may even lay down hands like AT and 77, but that seems a little too tight.  Regardless, with his assumed opening range here I think i would jam, and if he has you beat, too bad.  You really want to put yourself in a position to get 2nd or win, because that's were the major pay jumps occur.

We have 25% equity against a calling range of ATs+ AJo+ 77+.  That accouts for about 8% of hands.  He is probably opening 40% of buttons if he is loose, even at this stage of the tournament. 

so 80% of the time we win 750 K making our stack 4,864,761(.8)= 3,891,808

20% of the time our stack will be 2,037,455+ 444,850= 2,482,305(.2)= 496,461

3,891,808+496,461= 4,388,269 or +243,508 in chips.

The wider he calls, the less we expect to make to a certain point, but I think this is a pretty good spot to shove.  And ICM isn't a huge factor, as we are basically the same as the smaller 2 stacks.  If the other short stack not in that hand had 1 mill, then this would be a fold, but right now I think it's too good of a spot to pass up.