So... it's encouraging prostitution?

They're going to make their income via sex. They've made that decision. So increasing the age means their primary highest value product (themself) isn't available for commercial sale, only local sale. Limited maximum age reduces their lifetime career opportunity (and is a weird restriction, aside, I thought adults made their own life choices). Shortstacks being barred means, well, they'll seek their income somehow, probably through enjou kousai since the whole point is they might be confused for the primary demographic that does enjou kousai. And max one video is a random cap on earnings.

Either ban it entirely because it's an election-approved social wrong, or fuck off because it isn't the state's responsibility to police the careers of adults. This middle ground nonsense is just bizarre.