Why would you expect a fertility specialist to be of any use in learning how to advocate for sterilization? They literally do the opposite of what you are asking after.

Seems like you are asking this question just to troll - "I've heard..." Not you've experienced, but you've "heard". As someone who did seek sterilization and was declined, the answer, as with any other medical issue, is to find a doctor willing to treat you in the manner in which you wish to be treated. Sometimes that's easier than others. But in all of my search, I never thought a fertility specialist was the correct resource.