I love that we're having a whole hypothetical discussion about this. I think the time in the timezone where the rights were held probably took priority over the time for the poster of the image at the time of upload. Regardless of what timezone you post from, it would have been posted before midnight for Disney and the relevant courts.
Free speech doesn't apply to Intellectual Property at all, or rather you're free to say whatever you want but you can still be sued for anything that you say.
Trademark. Not copyright. And the part that is covered is Mickey.
This could also be covered under copyright, since the only Mickey that went into public domain is the one from Steamboat Willie, not this one. I'm not a lawyer, though.