(Notice that I'm not saying it'd be wrong to do so.)
Now, what Google could do without (additional) reprisal would be to have a front-page link to a page raising awareness of this issue. Run their own ads on YouTube and other Google sites. Spell it out in terms everyone can understand, with direct quotes from the most incriminating of documents about the smear campaign. Provide people with an easy way to complain to their congresscritters. See how fast the issue disappears and a new case pops up against the originators of the smear campaign.
The more interesting question is what chunk of movie revenue comes from Google.
Wouldn't this be akin to MS telling Dell it's going to yank windows licensing in retaliation for selling red hat.
I'd also argue that it's not technically monopolistic, but would certainly have negative consequences to the ??AA "partners" as well as chilling effects on others. But if Google wanted to take a nuclear approach, that'd certainly be one tack.