[matese]

Welcome to YT.

Males are neutered to eliminate testicular cancer down the road thus a longer healthier life for the dog, neutering also reduces / eliminates a males testosterone level which eliminates aggression.

We don't know they whole story on your boy as to what lead up to his aggressive behavior, neutering a dog as I have written above is a life saving procedure and should be done. He has ragging hormones and reason he is getting worse, neutering him now will help, his testosterone will be diminished it "may" not be eliminated without some training from you because some of his bad behavior has now become a habit that you have to train out of him. You cannot neuter and think he will do a 360 and become an angel. If you cannot train him on your own enroll in a good obedience school. They will train you and your dog the proper training technic. At home you must work with your dog no more the 5 to 7 minutes several times a day everyday with the training technics the trainer taught or showed you.
Who ever told you neutering would not stop aggression does not know much about dogs, if they did they would now the benefits of neutering male dogs.
Neuter your dog to give him a longer and healthier life. Also, the dog will gain weight only if you over feed him and do not give him enough exercise.
My dog has nipped several groomers, he is a rescue, we are a team for 6 years now. He may have had bad groomers when he was with his prev. owner. I had to change groomers several times due to, in my opinion bad groomers. He is with this groomer 14 months, although he is not a role model of a perfect dog to be groomed, he has not tried to bite this groomer. Find a patience groomer and stick to one groomer so he can build trust in the groomer. 75% of dogs are afraid of groomers.
Please keep us posted on your baby.