I don’t know if it will fix those whiskers on your ladder, but when my fiberglass ladder rails get worn from sliding them on and off the racks, I’ll use boat polish with a buffer wheel to smooth and clean them up.
It even seems to bring some of the old color back and makes my extension ladders extend and retract easier as well.
The only bad thing is that the sides of the rails can be quite slippery for several days afterward if they get wet or you happen to grab them with sweaty hands, but I tend to hold onto the rungs when climbing anyway, so not that big a deal for me.
I'll admit that polishing ladders probably sounds a little overboard, but I think it actually must help preserve them.
I still have one 28' Werner type IIA extension ladder with messenger hooks and a 6' step that I bought new, which are both now 21-years old and still in very good condition. I’ve carried them on my truck almost as long as I’ve owned them.