Texas law doesn't mandate that electors vote according to the results of the state's presidential election
Depends on the meaning of mandate.
My understanding is that an elector that does not adhere to the vote is replaced with one that will.
This sjw got his 15 seconds of fame. AMF.
This is the second elector on record who has vowed not to vote for Trump. In Texas, the electors are voted separately from the primary so there's no guarantee that they'll be loyal, and as you noted, there's no faithless elector penalty there.
The first guy resigned. Someone will fill his place, probably voting for Trump. This second guy won't resign; he wants to actually cast a vote for someone else (Kasich is the name being floated). That vote will count in the Electoral College if/when it is cast, and if there turn out to be 37 faithless electors across the U.S., an admittedly unlikely scenario, then it would go to the House, where they'd decide between Clinton, Trump, and whoever had the highest vote-tally among the faithless electors.