I wouldnt worry about it. I have 2 boys of my own and while I am growing coat they will always have topknots. I guess I am a little callus to it because in addition to the topknots I get all sorts of nasty comments when people see them in wraps.
Just be nice and play into it. I have some very creative stories I use when people make comments on the hair wraps
As long as your dogs are happy, healthy and well-cared for, if you choose to put a topknot or boy in his hair it is nobody else's business.
Btw--your boy is a cutie!!