Removing Joe Biden at the last minute doesn't magically transform a bunch of people who all said they'd vote for Joe Biden into an "open convention" www.indignity.net/who-elected-...
Modern conventions are basically 3-4 days of highly produced free advertising for your nominee. I'm sure 3-4 days of a last minute thrown together "Dems in disarray" open convention with no official nominee is exactly what we need right now.