My hunch is that it’s not so much that Platner was their man from the get-go, but rather that after AOC, Tlaib, Ilhan, etc, the establishment has stepped up their game in getting their tendrils into nominally progressive outsider candidates early. They’ve realized they can’t ignore them, and brute-force spending them into defeat is unreliable, so now there’s more effort put into weaseling their way into these candidates’ good graces if there’s any sign they might have a realistic shot at winning.