By default, you should be allowed to say that the president is a lizard person, and show your "irrefutable evidence". On national news? Only if you can persuade a national news show that they should (or unless you own a national network).

But if you don't own them, they're not going to show your "proof" (except perhaps as comedy), because they have a reputation they need to maintain. And if you own them, they're still not going to, because they'd lose reputation (and therefore market share), and they'd get sued for slander and lose.

That leaves you showing your "proof" to whoever you can persuade to listen, without going on national news. I'm not sure I see the problem with that.