Excelsior is only for CUNY and SUNY.
Was the first school listed for TAP a SUNY school? If yes, this is. why you may have been given excelsior. Excelsior is only for SUNY/CUNY.
Your son. maybe eligible for an ENHANCED TUITION Award (the application has not opened yet).
The Enhanced Tuition Awards (ETA) program provides tuition awards to students who are New York State residents attending a participating private college located in New York State. Recipients will receive $6,000 through a combination of their TAP award, ETA award and a match from their private college.
https://www.hesc.ny.gov/pay-for-college/financial-aid/types-of-financial-aid/nys-grants-scholarships-awards/enhanced-tuition-awards.html
Check to make sure that your son is attending a school that participated in the program. Many schools opted out of ETA, because they felt that the terms were too restrictive.
Schools that are currently participating in ETA