I get that Ukraine won’t consider the possibility of ceding any territory, nor should they. They probably don’t like their allies even mentioning it.
But, there’s the separate issue of not being able to join NATO with ongoing territorial disputes. Without much context to go on, I would almost interpret this as something more along the lines of “Ukraine could join NATO tomorrow if the dispute went away (by whatever method)”.
Go to Moscow, hang a left. When you hit the North Pole, head south…not, not that south, the other one! The other other one. After a bit, take another left for a couple hours, and you’ll arrive at your destination on the right.