I'm running with the following perspective:
To me, this means that, sure, Drow take surface elves prisoner.
But not anonymous level 1 ones.
I could see the OotA start featuring enslaved surface elves if it were a mid-level adventure. A level 7 or 11 elf would be quite a catch, and definitely something Drow slavers would resist their natural hatred for, something they would rather transport to Menzoberranzan, something too valuable for petty murder.
So while that might work for you, it won't for me. Enslaving level 1 PCs would devalue the Drow's reputation too much: if the first Drow you meet doesn't kill you, then there's not much to that so-called hatred, is there?
Anyway, that's the reason for this thread. Good luck in your game!