The problem can't really be solved by using a compiled language either. There are decompilers for every compiled language. The code won't be pretty, but you can figure it out enough to rip off what ever it is the obfu was guarding. Indeed, I recall seeing a proof that in a general sense, obfu is impossible. I can't find it on google scholar searches, and I don't recall the author. I did find a paper that showed deobfu is NP-Easy though (Appel). Not sure how relevant that is though
Anyway, I would say the only way to prevent them from seeing your code is to run it as a web service (or similar) so they can't get at the executing process.