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.

Thank you so much for that.

Can I supply you with some definitions of commonly used terms that I unilaterally decide you don't know, or would you feel that was condescending?

Oh, you were condescending from the start. So yeah, no need. don't expect another reply. It's been a real joy interacting with you.

No, I was being sarcastic. Look it up in your dictionary. (No need to post what you find.)