There’s also the fact that, while the recent AT&T/Time Warner deal might make a Comcast/Fox deal more likely, it’s far from a sure thing.
Also, if Fox goes with Comcast now, it will be on the hook for a $1.52 billion fee to Disney for pulling out of the existing deal, though, according to Variety, Comcast has offered to reimburse Fox for that fee if it ends up paying it.
The fact that Disney doesn’t own a cable distribution network for providing its own content could make that deal more attractive to regulators, and a successful $52 billion deal will result in a lot more money to investors than a $65 billion deal that never actually happens.
A Board of Directors has a fiduciary duty to its stockholders, meaning the Board is expected to do what is in their best financial interest, and while the higher bid price would mean more money in an absolute sense, the fact that a cash deal has different tax implications than a stock deal does change the math somewhat.