So the delamination is not on the basement, but on the floor where the slide is bolted in. I can see why Host would not anyone to mess with that. There would be no way to replace the delaminated piece without removing the slides.Removing the slides would probably incur more problems down the road, it would not be an easy job, especially if it is the dinete slide which is large and heavy.
It looks like the best fix is what Host recommended, short of taking the camper back to Bend, which is what I would do on my next vacation.I am not sure I would want anyone to remove my slides, unless I had more serious problem than what you describe.
As long as the interior floor is OK and only the exterior panel covering is bubbled, I don't see a problem with the aluminum panels.I would probably have asked for longer panels, so they would cover the length.