There has been some really, for me, surprising and interesting studies in recent years that indicated that trigger warnings are actually not helpful at all to shield people suffering from trauma from unwanted negative emotions and instead could lead to heightened anticipatory anxiety. According to these studies, they are also not generally effective in keeping people from watching the things they would react negatively to.
Here is the huge Meta-analysis of several studies going into detail:
https://journals.sagepub.com/doi/10.1177/21677026231186625
Very important: They differentiate, as they should, between general audience warnings in the form of the PG or ESRB systems and actual trigger warnings.
Intuitively, Trigger Warnings always made a lot of sense to me and I very much defended them, but I think it would be ignorant to ignore that there is at least evidence showing that they don't actually do what they are suppossed to. And if they don't , I think engaging with them on an artistic level and talking about how they negatively affect a piece of art and its storytelling is certainly worth talking about. So I get where he is coming from.