Well, first of all - yes, if you bring up speculation, a judge will tell you that's not admissable as evidence. In fact, a lot of the talking points that were pushed right here on imgflip were straight up ruled as hearsay, and did not see any court time at all.
If you bring up actual "proof" or evidence, NO COURT will declare it fake news, and no court has. If you have even half decent lawyers (which, frankly, for Trump, isn't always the case) the court will at least evaluate and assess the weight of your proof on the bearing on the case.
Your proof will be nullified if the court rules against you - but that doesn't mean you won't be allowed to catch future cheating efforts in a different election with different evidence, or even in the same election with different evidence. It just means that THAT PARTICULAR INSTANCE of your "proof" didn't wash.
So cut the crap. If you can prove it, prove it to a judge, and stop complaining that you can't prove it to your relatives in a Facebook argument because that's not how things like this are settled anyway.