Seriously... what went through the heads of those involved?! How were they thinking this was in any way something one could even ask a person in wheelchair?! I mean... you have somehow failed to get a chair with wheels on for some reason... how is you reaction "Yeah, get off my plane, you're in the way"?!
But when the plane landed, the flight attendant told the couple there wasn’t time to get a wheelchair on board before the plane had to prepare for takeoff again
That's a problem for the airline to explain to the delayed passengers of the next flight. Maybe if they didn't cram their flights so close together that there's no time to resolve problems from the previous flight they wouldn't have that issue.