TIH couldn't have sunk them. It was only $35M or so away from breaking even in theaters(if my 2X budget rule pans out) and that is easily mitigated by what a runaway success Iron Man was. and TIH eventually DID become profitable once DVD, TV rights got included(probably a tidy profit but one never the less). And that's not even counting other ancillaries like toy tie ins, etc. TIH may have made them take stock and realize that one good bomb could wipe them out so they opted for the security that Disney was offering.