If by "can't use it" you mean you can't make a mod for distribution, yeah, that bites.
You can however use it in a personal mod that you don't distribute. There aren't any rules I know of against it.
If you can find out who made the models you want to use, contact them directly and ask for permission. The worst that can happen is they say no, and you might get lucky and have them say "go right ahead". It's worth a shot anyway.
KF