There has never been a
Scamp that rotted from the bottom up, however there have been plenty that rotted from water trapped on the top from various
leaks from
windows and other penetrations.
If it is dried out then no harm no foul, but since the water will not
escape by draining out the door and once the wood is saturated it has really only one way out and that is out the top, past the floor coverings etc.
Of course having the bottom not water proofed won't help, as if the water soaks in and the floor stays wet the wood will rot no matter if it is encased in
fiberglass, resin or anything else.
Keep the water out and the floors will not rot.