Somebodys' sick idea of a joke. Same as the comments and texts about waiting planes and boats that got sent to Easten European immigrants here after the Brexit Referendum.
There are people who think this kind of thing is funny. If you found them and confronted them, they'd be "Look, we both know that won't happen, it was just a bit of fun!"
Only it isn't. It's cruel and upsetting to people who are genuinely afraid that their lives are about to take a severe downturn. But, of course,such people lack empathy and feel safe themeselves..
But there is no doubt that the election of Trump will make some people less cautious about what they say and who they say it to. That said, I foresee some States exercising their rights in the face of Federal pressure or Presidential censure. What the outcome of that will be, I can't begin to guess.