Trump has a lot on his plate right now, why is he even tweeting about this? This should be very low on his priority list.

I've heard the same response from Trump before when a "DACA deal" gets brought up, where he says SC must rule in his favor then get deal. Those "DACA deals" usually are in favor of DACA (USA ACT or better and not Goodlatte).

So Trump is hearing about DACA from somewhere. Maybe it's the support from the companies that they sent to the SC court case and he heard it in the news? Or his advisors are telling him he needs something immigration related before the election to win some latino votes back and/or people can't call him racist. Did the republican strategists finally realize that resolving the DACA issue in a favorable way takes a lot of talking points away from democrats?

Someone or something is bringing this to his attention, which is interesting.

/end of my conspiracy

Politically speaking, the Senate could be swayed to give DACA USA act or better and I think Trump can too but I don't know if Miller will allow it.