My puppy is named Jax too!
Personally, I could not stand to own an unneutered male dog. Jax's "male behavior" annoyed me so much I got him fixed right before he turned 6 months, the earliest age I thought it could be safely done. His behavior settled down after that.
I have researched what makes a breeder reputable as thoroughly as I could, and I would be highly suspect of anyone who made the offer your breeder is making. A lot of red flags there.