Self harm, short sleeves, and trigger warnings. What is fair?

Yesterday someone on /r/lgbt posted this picture of themself at a pride event, and several people in the thread commented on OP's self harm scars - one asking them to please and thank you spoiler tag the image and post a trigger warning as they found the sight of OP's self harm scars triggering.

As someone who has very similar scars as OP I said fuck that, I disagree. I found it offensive that the sight of someone else's scars somehow grants you the right and allows you to tell them to cover up or hide themself because they find it triggering. To ask to have trigger warnings and spoiler tags added is unfair, in my opinion - the commenter then replied that it's not that hard to do. But for me it's obviously not about the effort it takes to do it, it's about the fundamental principle of asking someone to cover up or hide their body that I take issue with.

OP said elsewhere that they have struggled with mental health in the past but moved on, and clearly they are now at the point that they feel comfortable or don't mind that other people can see their scars. And I certainly feel like they should be allowed to wear whatever they like. I think that showing scars like this is 1) brave, 2) helps reduce stigma surrounding self harm, and 3) should be entirely that person's prerogative - their body, their choice.

So I am curious what you all think about this?

Is it fair to expect or ask someone to tag their picture like this, to hide their scars, to cover up, etc.?