I interpreted that as something which could have rescued the ride, rather than necessarily a flaw itself. It also suggests that making
@Stevec047 and friend start in the last group wasn't any sort of attempt at grouping similar-speed riders together - possibly even the opposite, putting them in with a load of racing snakes on glam bikes to get them dropped near-immediately and isolated.
I wonder whether the organiser did indeed "make sure [they] got to the rest stop" and whether there was any attempt to find out what happened to the lost entrants. I'd expect a sportive not to abandon riders unless the riders abandon the sportive or it's been explicitly described as a no-prisoners or race-the-broom type event.