Hi @maeono welcome to our Head and Neck group.
Your brother as a patient or you on his behalf can question the path his doctors/oncologist want him on. Proton therapy for one can be performed anywhere it is available. It is common to have radiotherapy done elsewhere other than where the surgery was done. Just ask the question.
Keytruda and other drugs have been quite successful in helping to attack HPV16+ marker SSC. Again, if docs are not familiar or encouraged by this tidbit, perhaps your brother is in the wrong place or with the wrong doctors. Ask about the experience in Squamous Cell cancers, not about cancer in general. For example my oncologist performed radiotherapy hundreds of times yet I was his first tonsil SSC patient and in his entire career he had only one other after me. Mine was a bit botched but I’m alive 22 years later.
Don’t let them remove his other tonsil. It is a handy filter in case the cancer should try to return. 30 lymph nodes is already way beyond necessary in my opinion. Let’s just keep cutting the limbs off the tree until all the leaf bugs are gone eh? “First do no harm.”
Please ask the questions and if the answers are unsatisfactory then keep asking. HPV SSC is quite treatable and has many advances in treatment just in the last few years. Egocentric doctors seldom have advanced for centuries. Choose wisely.
Have you explored other options?