Would you pay money to exercise those options?

If you don't expect them to succeed then staying a full year for the options is pretty pointless, since they typically expire in ~90 days after you quit.

No - staying primarily to avoid the "job hopper" label, and to finish documentation coverage so that I can avoid burning bridges as much as possible - I am solely responsible for the portion of the product that I work on, no one else at the company even knows the language it's written in (which isn't particularly obscure). There's no way they'll be able to hire a replacement within two weeks, so documentation will be all they have to go on.

So who made the decision to go with that language?

Apple? NeXT, I suppose?