The proposed time zone is to drift about 1 second every 50 years. I also suspect it wouldn’t really be a time zone in the same sense as the time zones we know - it would just be a standardised calibration reference. Dates and times expressed in “moon time” would probably just be some leap second off of a known Earth time zone, and because it’s mere seconds over centuries, I think the only use of this time zone is to calculate ultra-precise time diffs between two earth datetimes when the observer is on the moon. At least, that’s how I interpret the articles I can find about it.