I went to Brassard somewhat over a year ago, and I took his word for it.
Zero regrowth, and it seems likely that by now I would have seen something if there were going to be. It may be because he basically didn't use scrotal skin inside; all of that originally hair-bearing skin appears to have been used to make the outside of the labia majora (which has hair in cis women, too). Regardless, I picked him in part b/c I didn't want to do genital clearing, and I haven't regretted it so far.