Adult content is opt-in and age verified on steam.
Making an “adult content” launcher would just give more targeted scrutiny. It’s like saying, “here’s the target for you Puritans to attack the while company over!”
The only way I can think that kind of obfuscation could work would be to have the adult content launcher run through a secondary company under license to use steam software. But then, there’s still the pay processing issue, and that license could violate the processor ToS anyways.