Training on the use of defense articles is regulated under ITAR as a defense service. I'm not sure that training on semi-automatic firearms would be regulated by ITAR though, as opposed to EAR regulation, and with the EAR I'm not sure if defense services is regulated (or, rather, training on a dual-use item).
There's all sorts of related stuff that is popular in training courses which could be a regulated defense service under ITAR, I believe. Body armor, lasers/NVGs, etc.
Lastly...even if it is a regulated defense service, that doesn't mean a violation occurred. He may have even legally owned all the guns pictured, as neither citizenship or LPR status is required to purchase a firearm...there's just some extra paperwork.
ETA: I should caveat that I have no specific training or experience on ITAR or counter proliferation enforcement. This is just from my own readings when talking about it with other buddies like @HCM.