The state should replace him.
I believe I read that he signed/pledged to support the chosen nominee and eventual winnner at the Texas Repub convention. Anybody? If he is in breach of that (legally binding?) he should be removed and replaced.
If he were saying he was going to cast his vote for another viable candidate (one who actually had a chance to win), then I might say that was in keeping with the original intent of the electoral college.
In this case, he says he is going to throw away his vote on an inconsequential candidate, possibly Kasich. He is effectively removing a vote from the only tally that counts, the same as if he were voting for Bugs Bunny. It might be cleaver when the general voting public does that, but electors are supposed to take their jobs more seriously, since they are casting a vote that represents millions of us and not just themselves.
He is irresponsible and abusing his position to make a petty, personal statement. He has a solemn duty to do his best by the people of this country. This is no time for grandstanding. I think he should be removed, if at all possible, because his disrespect makes him an inappropriate choice. It would send a message to the other electors that We the People are not to be trifled with.
The way the first elector resigned for his personal objection to Trump was respectful of the process. There is no shame in recusing yourself.