You can see just how insane this whole thing is when a man who was castrated didn't realise that it would impair his sexual function. To anyone on the outside (with experience, for example, of castrated cats, dogs, horses, cows, sheep, etc.) it's the whole point of the op.
Just so it is clear, it is completely possible that he didn't realise this. I have read enough posts by men about gender affirming surgery to know that they are not realistic in their expectations, egg each other on with ridiculous, impossible expectations and that they silence any doubters or regretters. The surgeons are also to blame. I wonder how many surgeons in the gender affirming surgery field have psychopathic or narcissistic tendencies?
The whole 'people regret other surgeries' is a dishonest minimisation. The important distinction between plastic surgery to correct/repair a physical issue and gender affirming surgery is that the latter begins with a physically healthy patient.