Well, no, they didn't. They voted for a slate of Electors who pledged to vote for the Republican candidate. This guy is reneging on that pledge, and should be blackballed from the GOP from now on.
But, this is also the base rejection of the "Hillary won the popular vote" meme, because neither Hillary nor Trump, nor any other Presidential candidate won a single vote anywhere. What people were voting on were slates of Electors, and in most States the Electors were decided on 50%+1 margins. Any "popular vote" over 50% is meaningless for any particular State, which is why Hillary's numbers in California are meaningless. She got all 55 CA Electors already.
If anybody is being "disenfranchised" by the current "winner take all" set up, it's folks like the 30% or so GOP voters in CA, who saw 100% of the California Electors go to a single candidate.
Does Texas have a “faithless elector law”?