I can understand that. I have my own serious misgivings about her, both current and past, and I wish we'd had more choices this time around. But at this point, we're pretty much locked-in with her as the nominee. She's the vessel of our hopes for this cycle, for better or worse; progressivism's prospects are now directly tied to her. If she loses, it's game over for many of our causes for a while.
And the thing is, we've tried arguing the cold, logical, guilt-free route on this theme for a while, and it largely gets ignored from the BernieOrBust crowd. I'm sure you've seen this dynamic at work over many threads over the season. But they're big on emotion - they loooove emotional cues - so it doesn't entirely surprise me when a change in argument tactics is made. If you can't entice people to think, and they're across the table singing obsessively about how they feel, communicating via meme, it makes sense to try to influence those feelings. So here we are. Someone has matter-of-factly painted a few realistic snapshots from of one of our potential future timelines, and it's actually hitting nerves.
I get the hesitation on her, and it'll be incumbent upon us to keep the pressure on her (and our reps) should she win.. but an "MyWayOrBust" movement is suicidal.