That is really not Trump benefiting Republicans, it is more related at how the mainstream media did manage to get the political money gravy train that comes every 4 years to arrive much early.
True, no doubt. Of course, he would vote for any of the “terrifying” Republicans before he’d vote for Hillary, I think. So it’s probably a lost cause.
And that’s where I do think the general gist of the OP is correct. For “sane” Republicans (you may define this however you wish), having Trump and Carson up there on the stage could very well make it easier to pull the lever for Rubio or Bush.
The down-side, of course, is that one of the crazies actually wins. But that’s still a very unlikely event, IMO.