Based on the negative reactions I've seen (which are out numbered by the positive), you'd think Monte Cook Games was the RPG Police and they're coming to shut your game down if you don't download and read this free PDF and then share it with your group and force them to abide by it.
No, nothing like that, although now that you bring it up, it does raise for me a question I hadn't considered, and that is "Would they like to be the RPG Police if that was an actual possibility?"
My negative reactions are grounded in:
a) This is a ridiculous way to view most normal gaming interaction. If in 30 years and a dozen different tables this advice doesn't resonate, despite having been in situations where I wasn't happy with the content or having had players come to me and reasonably explain why they weren't happy with the content, then perhaps it's not advice grounded in reality.
b) For situations like conventions and the like where guidelines are needed, this theory grounded in the notion of a 'veto' doesn't provide helpful advice and indeed may actually be harmful to enabling gaming among strangers. Not to put too fine a point on it, but perhaps something like what people screening movies do with publishing ratings and a list of potential story elements would provide better guidance to strangers regarding how to have mutually enjoyable experiences and how to know how to proceed if those guidelines aren't adhered to. Maybe conventions should require people running tables to disclose what they plan to run, and share violations where their were complaints that content introduced by GMs or players didn't match the labels in a wider convention community. Comic book codes and family friendly codes aren't necessarily a bad thing. And you can always have your R rated and your X rated tables if you think supporting that freedom of content in a public space is worth the risks.
And maybe we just should be dropping "consent" as a highly loaded term, because as soon as you start introducing "consent", I suspect you are going to start drawing in all the other language of sexual assault into situations that aren't sexual assault. And if they are actually sexual assault, you have a very different problem than "Hey, my dad just died, and I'm not ready to process a relationship with a fictional father." or "Hey, I'm an arachnophobe IRL, and your language while admirably evocative is a little too immersive right now.."
c) For situations that are actually threatening there really isn't a lot to say except you probably should exit that situation forthwith, and hopefully this doesn't require much explanation. Like, if you find yourself in a group that seems to object to you personally (or think of you personally as an object) for whatever reason, this isn't a situation that can be resolved by a pamphlet.
d) Again this language of "consent" seems to be borrowed from spheres and ideas outside of gaming. I confess I'm a pretty naïve old man, but are we talking about gaming or are we talking about the S&M/bondage community in this thread? (I mean it occurs to me that this advice might actually make sense for situations where only two people were in the game.) Do we need consent language around the idea of board games? Movies? Books? Card games? Not sure really why my hobby is so different than normal human social interaction or conversation. Maybe people really are playing different games out there than I am, but a pamphlet like this just makes the hobby seem a bit skeevy to me. Is it really that skeevy and I'm just naïve and sheltered? I mean, if a GM handed this to me at the beginning of the game, I'd be like, "You know, sight unseen, just that you feel like something like this might actually come up, I don't think this table is for me." If I didn't know anything about the hobby, and one of my first experiences was this pamphlet, I think I'd be discouraging my children from being involved in so dangerous of an activity.
e) I had to google up "edgelord" to find out what that meant.
And I'm really trying to understand, "Is this just me?" But in researching that, the first thing I find is a video by a guy wearing a Red Army cap, who just as a first approximation probably is culturally and politically quite far from me, and yeah despite the vast differences in culture and beliefs and likely normal content at his table, he's got more or less the same take I do. And that makes me think, maybe it isn't just me, maybe it really is the authors of this pamphlet.