The power limit would be 15 W EIRP under that provision. It's basically useless to amateurs
The TX power limits were primarily driven by builder/operator safety - higher power requires higher amplifier voltages. If there is a lower requirement for a band to avoid interference with shared uses, why not just specify a lower power level? Why add a requirement that involves antenna and near-field environment modeling?
I support less limitiatons for ham radio operators, but 15W eirp is really not that useless.
I semi-routinely spoke to Japan with SSB using improvised antennas in the field with 10W.
Elecraft KX3 + Buddipole Deluxe. Doubt I was very efficient, though I did try to get a couple good counterpoise wires going.