Another factor may be how separate Sony keeps its entertainment division from its manufacturing division. If they're all free-standing divisions, with 'Chinese walls' (or Japanese walls in this case) between them, then Sony's tv and electronics may not be able to benefit from the sale of their ents division - it all depends on how creatively their accounts are set up.
And it should also be remembered that Marvel studios are notoriously thrifty. If Spidey's right go up to the highest bidder, then, while we would all like to think that Marvel is the webslinger's natural home - but they could well be outbid by another studio.
Or Disney could buy the rights to Spider Man, that would be the next best thing. No one
has more money than Disney. If they think they'll profit by giving Marvel access to Spidey, they'll spend the dough. It would be peanuts compared to what they spent getting their hands on Star Wars.