If you keep your IR current the ATPL theory credit will never expire anyway. So I can't see your point right now. Do you consider to let your IR lapse? Why? All it takes to keep it alive is one checkride once a year. If you have a well paid outside aviation job it shouldn't be such a challenge to afford at least that one flight. And if you intend to do freelance GA jobs a current IR would also clearly be an advantage, don't you think?