His scurs look small to me. Once castrated, you should be able to show him regardless of small scurs, but email your local 4H leader to ask about the maximum size.
We have reburned scurs on our own but they do need to be small still and it is not something that I would have done without experience.
In our area there are no 4H buck shows at all. (And we go to quite a few shows.) There are 3-4 ADGA sanctioned shows a year for Nigerian Bucks in this state, but they are open shows to anyone. The only 4H shows I've seen with bucks/wethers are for boer or market goats.
We have a goat mentor who has been into dairy goats over 30 years that has been really successful in banding horns and scurs. She's even working with her vet to come up with a protocol. Generally scurs on bucks don't disqualify from showing unless they are over 1" of horn sticking out. I've seen judges be very liberal with curling and mis-shapen scurs on bucks too. My Nigerian buck gets scurs, but he always knocks them off during breeding season with minimal mess- either from rough housing with the other bucks or when I breed him with my one horned doe.