I don't think this is really possible with NXOpen, since people could just record a Journal while running your obfuscated Journal, thus getting the whole execution path in "plain text". I guess you can try something wild, like nested cycles making tons of random garbage API calls to make the recorded journal a pain to read, but true obfuscation in an API that has a built-in "show every API call a plugin makes" function seems rather hopeless.
One thing you could do is write not a journal, but an NXOpen C program using only the ancient pre-obfuscated C calls, left over from the time NXOpen was just made "UG Open". Many of these calls are not supported by journals, and even if they are, the reverse-engineer guy will hate your guts for having to learn that, say "uf5300(ra1,ra2,rp3,ip4,&nr5)" is used to create a cylinder. Of course, you'll have to learn that yourself first, making this a rather sadomasochistic experience.
[Edit]
Actually, looks like "NXOpen.JournalManager.IsJournalRecording()" can be used to take care of the "reverse engineer by journal" problem. So I guess you can write a "regularly" obfuscated .Net plugin using this function to lead your wannabe hackers on a wild goose chase. Of course, that call itself be detected and skipped by any halfway competent hacker, but you make a thousand of these calls... :-D