A thought on trigger warnings etc. speaking only for myself...I work in Holocaust education at the moment, specifically looking at photographs of atrocities. I look at and think about a lot of very horrible things as my actual job. This is, as I'm sure you can imagine, not very pleasant. I'm never going to be fully desensitised to it but I can maintain some critical distance in order to do my job.
If someone springs a horrific image or a graphic description on me without warning, when I haven't had chance to get myself in the right frame of mind, then it will have a strong effect on me. My brain will automatically connect it to similar images or draw comparisons with other graphic descriptions. This could go on for hours. From experience, the images will make their way into my dreams. I'll dream about friends and family members being in these images, having these things happen to them.
I'd like to be able to choose to avoid certain topics and material sometimes not because I'm a coddled, fragile little snowflake who needs to grow up and accept the real world for what it is, but because I want some control over when and how I encounter this material. I need to carve out a few hours every day when I'm not thinking about genocide, sexual violence, dead bodies etc. so that I can carry on doing this work. Deny me any sort of space which is reliably safe from this stuff and I will have to quit. Just a quick heads-up about what's coming is enough for me to mentally prepare myself, or remove myself from the conversation for a bit. That way you can carry on having the conversation without the interruption caused by my turning green, going dizzy, putting my fingers in my ears and trying to think about kittens, or (for repeat offenders after several warnings) throwing my drink in your face and never coming near you again.
This is a plea from someone who's never been the victim of an attack or witnessed anything traumatic. If someone who *has* been through a traumatic experience asks you not to spring something on them without warning, then don't bang on about free speech and victim culture. Treat it the same way as an allergy: you can make all the peanut butter cookies you like so long as you warn people what's in them.