You can run an SWG and lower CYA levels, if that will save a marriage then do it. ?
The higher CYA levels better protect the chlorine generated by the SWG. Less chlorine burn off to the sun means less chlorine required of the SWG. Less chlorine production means longer cell life. That's really all it is, if the SWG can keep up with the higher UV losses then it is just as safe.
Regarding the misconceptions here, CYA buffers chlorine at a set amount. If you look at the SLAM levels they are all the same, 40% FC to CYA. And they all provide the exact same active chlorine level, which is less than a pool with zero CYA and 3 ppm FC. You might recognize that example as a pool that is within CDC/WHO guidelines, yet would be far more harsh on people, swimwear, and pool/equipment.
Government agencies don't recognize the effects CYA has in the water. Yet. There has been recent movement, but change is long in this industry. Follow what you wish, but just know that when it comes to this we have the science backing us. Did the WHO provide you with the science to back up their recommendations? Or are they just being taken at their word because of their name? I don't expect an answer, just something to think about.