Well, your costume is wonderful. And we all can see the leftover dye residue on the exhibition photos.
The real question is, why do you want to join the 501st? Is it to be able to troop at Conventions or non-Con events (children's hospitals, food drives, etc)? Is it to make friends with fellow costumers? Is it for the pride of saying that you're 501st? These are important questions to ask (seriously). You don't need to be a member to see upcoming events on most of the garrison sites, and anyone who would turn you away is clearly missing the point of costuming, and/or doesn't know much about Boba Fett. You can be like Frank Sinatra: hang out with the Mafia without ACTUALLY being a member.
The mere fact that they don't have a fully-updated RotJ Fett page says a lot (no gauntlets? Seriously? No hip pouches? With completed Snowtrooper and Biker Scout CRLs?). We know far more than they do, and we have for many years. It's not because we hide or hoard information. It's all right here in these pages.
I've had long discussions about the 501st with several guys in our little group. Every time I read about this kind of stuff, it really gets under my skin. Your costume looks wonderful. You know it, we know it. I don't think that you need approval from the 501st to confirm that.
And don't worry, your submission pic to the 501st was a lot better than mine: