As you are p16 positive this means you are HPV positive. So you should respond well to chemo radiation therapy. Tongues usually deviate because of Hypoglossal nerve damage. Is there a lymph node compressing the nerve?
It's probably a good idea to get a 2nd opinion. Even if just for peace of mind that your treatment plan is correct.
Tammy

Caregiver/advocate to Husband Kris age 59@ diagnosis
DX Dec '10 SCC BOT T4aN2bM0 HPV+ve.Cisplatin x3 35 IMRT.
PET 6/11 clear.
R) level 2-4 neck dissection 8/1/11 to remove residual node - necrotic with NED
Feb '12 Ca back.. 3/8/12 total glossectomy/laryngectomy/bilat neck dissection/partial pharyngectomy etc. clear margins. All nodes negative for disease. PEG in.
March 2017 - 5 years disease free. Woohoo!