I have certainly said nothing that suggests I'm in favor of anyone being forced to do anything. In the case of the unfortunate friend who is invited to go to a seafood restaurant, if he is allergic to seafood, it may be incumbent on him to politely decline citing his seafood allergy as the reason. Of course, the potential host will probably express disappointment, and be forced to make some sort of apology with respect to the fact that they had already planned an evening at a seafood restaurant, and will make some sort of suggestion that they be invited along the next time they are going out to somewhere other than the seafood restaurant, and this is an uncomfortable situation for everyone.
But the point is that the person is neither forced to eat seafood, nor is the group forced to change their already well made plans. No one is forced to do anything.
Nor does the consent document force anyone to change ‘already made plans.’ It’s a tool for establishing what you will or won’t include at the table. And that once established, you don’t include things that you agreed to exclude from the game.
If a new player wants to join, but it turns out their deathly phobic to something that features heavily in the game, then you explain that to them and they can opt out. The document doesn’t insist you change that, it just means that you establish he’s phobic before you start playing with him.