I guess it depends on the approach to it.
Is it a "I have x money, I need more" or is it over the principles of it? I've seen a few articles talking about the potential shift of how contracts work in Hollywood because of Disney's actions here. Apparently a lot of Hollywood contract law between actors and studios have had a history of a certain vagueness and done in the spirit of the contract rather than worrying over every single dotted i and crossed t.
If your contract says you'll get a bonus figure depending on x factor, but then the studio deliberately did something that made x factor smaller even though they said they wouldn't... Would you not say anything because you've already got a good amount and accept it or would you call them out on it and make a fuss?
Eh, who knows the specific reasons behind it. With the amount of crap Disney regularly pull to keep all the money and not let it trickle down to the other people involved in processes, I'm inclined to give Johansson the benefit of the doubt on motives here.