“...and despite him being in the USMC, he went to Ranger school and Airborne school.”
?? Sounds unusual...?
Not unusual. Especially Marines attending jump school — which is literally run by the Army for all the services. A few Marines can apply and be accepted to Ranger School. I recall seeing a Marine NCO competing in the “Top Ranger” Challenge(or whatever it’s actually called) where competitors pair off to compete.