I don't see that as him being "triggered". If you actually read the comment he clearly states that he isn't sure to what extent (if any) RT implementation will have in alleviating the game's flatness. He saw a common criticism in the game looking flat (which it does) and decided to break down a range of lighting techniques at use in the industry and highlight how the demo did okay with those in some areas, and failed in others.
Personally I liked his, NXGamer's and Cherno's analysis of the demo and all three kind of focused on different things pertaining to it. I don't get the persecution complex some of you have against people like Alex on this thread or in general particularly for, in this case, not tearing the demo a new asshole. The general sentiment from their analysis is that the game could visually be better, and he wanted to focus that on the aspect of the lighting to distinguish what they're doing is different from static light sources but, of course, comes with its own complications.
And let's keep in mind they're on Era of all places; they certainly can be a damn crappy forum a lot of times even on video game-related topics. If people are taking statements in their video out-of-context or exaggerating them, he has the right to defend himself, just like any other content creator. I don't agree with him that the lighting was the largest factor for the game's tepid visuals in a lot of areas per-se (I think NXGamer's and Cherno's videos highlight those larger factors pretty well), but I don't think that invalidates anything Alex has mentioned regarding lighting, either.