I don't think Scyld would. He's pretty much figured out by now (even if he won't admit it) that his best bet is going to be to throw his lot in with Linduial. He's also smart enough to know that if ransom money hasn't come yet, it won't. He and Linduial had worked that out (if rather uncoopertively
) in the first days.
I'm playing over scenarios in my mind, and nothing's fitting. I don't even know where Scyld would go with Lindiual if he did run away with her (say, because Sorn wants to kill her after hearing of the rescue party - except I think Scyld would be more likely to just kill Sorn than run away); he doesn't have a home somewhere, he can't go to Edoras and or Dol Amroth and Minas Tirith wouldn't be too hot of an idea either. He's not exactly the sort to go hiking up into the mountains. Bree? That seems about as likely a destination as any, I suppose.
But I really don't know what would happen if Sorn were to end up dead before the rescue party got there. That would be a really weird position for Scyld - what's he supposed to do with Linduial? Just letting her go won't seem just right, but he's not going to run off with her either. And when the rescue party gets there - "oh yeah, she's down in the cellar, let me get her for you"? I don't know. This would be rather anticlimactic however you look at it - Scyld isn't so dumb to fight a whole rescue party, and he wouldn't have any good reason to hold Linduial against them.
I don't know. Unless some of this sparks an idea?