I don't understand how there isn't a floor on the age for lifetime Plat. AFAIK to get night credit, the room must be booked in one's name and paid for by the person. So this would require being old enough to have a credit card and sign contracts, which I assume would be age 18 in most jurisdictions. (In addition, most hotels do not permit minors to check in and stay without adult supervision.) Hence the first year as a SPG member who earned Plat status would seem to be the year the person turned age 18, which should mean that no one can be lifetime Plat before age 26, as the tenth year of earned Plat would therrefore be the year that the person turns 27.

Where is this logic wrong?