I think of the situation as not wanting to bring your young adult back into your home as a "dependent child" which they certainly are not. They need to retain their dignity and independence as an adult. The hardest thing I have had to do for my son was to allow him to be a man. I have a tendency to want to be the "fix everything" kind of mom, and logically I know that is not in his best interest.
It is difficult enough for an adult to "return home because of temporary situations of need." IMO, putting them back in their old room, with the old family schedule (whatever that may have been) reinforces too many dependent memories, and can be a stumbling block for them to advance to the next stage of their life. There's nothing wrong with temporarily returning home for valid reasons. Just bring them back as an adult, and share your life - don't make them feel you are sacrificing for them. That has a way of dumping unintended guilt on them, and impedes their progress and the enjoyment you can have together in the adult-to-adult relationship that you both have earned.