Bellingcat? Really? You know they're a cutout for the western spy agencies and can't be trusted ever. They get debunked on the regular. The guy that supposedly runs it says he got his training playing video games!
He is citing Bellingcat - an outfit that has been thoroughly discredited and who's only use is as a cutout for spy agencies to spread their lies. Not ad hominem. Just facts. Here is the definition in case you were wondering:
ad hominem:
adj. Attacking a person's character or motivations rather than a position or argument.
adj. Appealing to the emotions rather than to logic or reason.
n. To the man; to the interests or passions of the person.