True, although using the same logic, my optometrist stands to profit from me continuing to need scleral lenses .

It's just that his logic sounds rather compelling - Keratoconus patients already have thinner corneas then normal, and PRK will disrupt the structure even further, making them even thinner in places. If CXL done at the same time is effective to strengthen the cornea, great - but if it doesn't (and CXL often needs to be repeated) you are now in a much more precarious position.