Ra, I think the disconnect here is that while yes, one can simply close the relevant tab, in the context of hypnotic triggers the "damage" might a

eady be done. If someone is receptive to text triggers, then closing the tab ceases being an option. I don't think you're intentionally not getting the point, but I feel like there's a difference in how we're looking at the topic where some of us see a problem and others don't.
I'm going to stray away from the strictly Bambi Sleep-related topic to try to present my point with an example
from my own life to see if it helps bridge the gap we're seeing here.
A handful of years ago, I was single, inexperienced with what was a fairly new concept to me in erotic hypnosis, and letting that leak just a little too far past what would be a healthy boundary and past the then-shallow cognitive defenses I've since built up. I encountered a hypnodom that was approachable enough for me to get into a dialogue with, and we started chatting on the platform YouMustObey (a hypnosis-focused social media which I no longer frequent). Sparing the play-by-play details, I found myself triggered into a state where I was willing to not only enter a voice call with him, but also to
give him my phone number. I was very aware of what I was doing, I was even growing increasingly nervous and getting bad vibes off of him, but when I tried to withdraw, I'd just be triggered again, and couldn't bring myself to fully pull away. I ended up having to wait until we weren't talking anymore to block his number and completely cut ties between our online presences. This was thankfully before I started using Discord, because if it had been on there then I'm not sure I could have gone through with all that.
For the record, I don't think sam_henry was being malicious (a bit rude, but not dastardly or anything) and was more just catfishing for roleplayers rather than intending to do anything harmful. But I think that that sort of behavior does set a nasty precedent that can very quickly get away from just testing to see if someone is faking it or not, because if a malicious party
does find someone receptive to text triggers, then that's much worse than whatever sam_henry was doing.
And again, giving consent to one thing does not necessarily mean you give consent to another. I'm not entirely sure what point is trying to be made with "it can be retroactively withdrawn", but I feel like it's kind of missing the point, because from what little we see of that conversation it doesn't seem like there was anything retroactive at all. I also don't understand the whole thing about the title of the series being used as a non-consensual trigger, because there is a difference between just using the series's title and intentionally triggering a specific person.
this is why open triggers are dangerous, folks