With that warning I would be very reluctant to put it in the AK 550 tires. I can't answer about the TPMS being sealed or unsealed but my personal option would be to avoid it just in case. The only reason you would need more than the warning that TPMS gives you is if there is a catastrophic loss of pressure in the tires. But I'm not so sure that what would cause that could be sealed by anything you can put in the tires anyway. TPMS will give you plenty of warning of any slower leaks or punctures and there are less invasive ways to resolve such issues, at least as far as possible damage to the TPMS.