We are talking about serious stuff in times that can lead to WW3.
I am human and can get emotional about it.
Throwing a 'source' at me from RFE, an entity which is universally known as a US propaganda tool could in itself be seen as an insult and questioning my intelligence.
Besides that, my jab in return was quite mild.
Especially considering the vile insult that get thrown at me constantly by others if I dare question the western narrative.
That puts me in a defensive state already.
Regardless of all this I ended the conversation with:

Thanks for listening, and dissagreeing without arguing or insults. Have a good night.

We ended on good terms, he is OK with it, so should you. You made your point.