“Romney would not be installed to win, but to prevent a winner and throw it to the convention.”
I see some kind of chicanery to insert Romney as the nominee at the convention. Otherwise, yes, he could only serve as a spoiler if he stalks out into the race at this late date.
I think the GOPe is so depraved they would consider Romney as a spoiler to be a win. Putting Cruz in as VP would mollify a plurality of conservatives who will still sit up and beg for biscuits.
They threw Quayle in with Bush the First to mollify the conservatives, and then spent the next 4 years destroying him.
Cruz should beware who he supports.