I’d actually commend them and give them financial advice regarding it’s longevity, it’s a high income job but your income drops as you age so it would be good to put a lot of it away or invest some in a secondary income source for when you transition out. This is also true for many other jobs which are reliant on peak physical function/visuals such as modelling or professional sports

Why do I care about the difference between using your hands to rub someone’s muscles (a massage therapist) and using a different body part to rub a different body part?

There’s nothing special, secret, or wrong about having sex, it’s just a normal everyday human activity. Use appropriate protection and go for it.