OK, so he saw this: "Joe Rogan has been saying this for months... and Bill Maher just had a segment on this last week. I'll go find it." and responded with a general attack on Rogan. You then asked him if he disagrees with the idea that COVID hits obese people harder. And he seemed offended by that question (he appeared to be objecting more to the tone and maybe implied agreement with the thread title--i.e., that COVID is nature/God's wrath upon fats) and then asked you if you think fat people should be valued less by society, which seemed to offend you.
My take is that neither of you was being dishonest, but both of you were being ungenerous and overly aggressive. Though he was just asking a question, he did imply a harsher anti-fat position than you took; and though you were just asking a question, you implied a belief he didn't hold (or possibly that objecting to the tone of the thread title was equivalent to disagreeing with an uncontroversial fact).
Good piece here on what I see the issue as between you two:
https://astralcodexten.substack.com/p/trapped-priors-as-a-basic-problem
I recommend the whole thing, but the most-relevant portion: