With a peanut allergy you have it and don't consume the food to avoid the adverse effects.
With a trigger warning you simply don't consume the content. Ideally, this is posted on the syllabus, so that the amount of time wasted arguing about this is minimized.
The article doesn't really "address" anything, it just makes value statements. For example, this paragraph:
> Consider a meta-analysis of 39 studies in 2007 by Sam Houston State University in Texas that found a ‘clear, consistent association’ between using avoidance-based coping strategies (that is, staying away from upsetting stressors or avoiding thinking about them) and increased psychological distress. For a more concrete example, look at the findings from a study, published in 2011, of women who witnessed the Virginia Tech shooting of 2007 – those who tried to avoid thinking about what happened tended to experience more symptoms of depression and anxiety in the months that followed.
You could say that the association is that people who avoid their traumas are more depressed and anxious, but you could also say the reverse, that people who are more depressed or anxious try to avoid the traumas that caused those things in the first place. It's an association with no causal link, so you don't know which direction the association runs in or even if one is directly caused by the other.
Trigger warnings are an avoidance mechanism, period. The only difference between this and a peanut allergy is that people don't feel the need to moralize about how we're enabling peanut-avoiders like it's a bad thing.