That actually increases his chances to win. If nobody gets 270 electoral votes it goes to the House. I think they get to pick from the top three electoral winners which would almost surely be Clinton, Trump, and McMullin.
I doubt they would pick McMullin.
Pretty unlikely though. 538 has Clinton at 332 votes without Utah. McMullin and Trump could actually split the Republican votes in Utah and let Clinton win. It all depends on those Mormon women who could be secret Clinton voters. (Apparently not all that uncommon for married women to tell pollsters they go along with their husbands choice but to vote their own in the voting booth. There's a good reason you go in the voting booth alone!)
