Of course if they went to court, X would have to prove what they claim. And ADL would probably have to do the same. It's the normal course of things between private entities.
In the meantime, the ADL has already threatened X with reputational damage, and now Musk is doing the same with the ADL- by spreading the idea that their motives are not necessarily laudable. I see a perfect symmetry in the situation.
> the reason I quoted Sartre in that post is that I believe there is no sincerity to this. Selecting a Jewish organization...
Basically what you're saying here is that your judgement of the situation is biased by the fact that the ADL is a Jewish organisation. Should Jewish organisations not be engaged directly or asked to be accountable for their actions?