That's pretty simple. Some--even many--Republicans are infatuated with Trump. I find it equally mysterious that many people interviewed at his rallies wax rapturous about anything he says, no matter how stupid or nasty it is. A lot of those people are vehemently anti-abortion, because they are in large part men who don't understand the issue, but they'll nonetheless accept Trumpty's wishy-washy stance, at least for now, because he turns them on.
Or are we supposed to seek out and approve of straight propaganda, at least if it's from the left?