There are several problems I have with this chapter but I will try to be brief.
1. Medieval Europeans were not stupid, there were good reasons why they ate what they ate, (ref. What Did Peasants Eat in Medieval Times
https://youtu.be/WeVcey0Ng-w). The cooking methods, especially for peasants, were simple because it was expensive otherwise. Even if you did have all your modern ideas in hand it would still be very expensive to do. And to say that all Medieval food was bland mush is just inaccurate.
2. Culture shock is real, especially if you don't have speedy information exchanges. It took years for americans to accept Sushi, however there are alot of cultures around the world that eat raw fish besides Japan (ref. List of raw fish dishes
https://en.wikipedia.org/wiki/List_of_raw_fish_dishes). In pre-industrial civilisation it is unrealistic to have fresh fish even a couple miles inland, so assuming they are not from a coastal region, their initial revulsion is realistic. But to be fair, if you are with people you trust you are more likely to try food that you have never tried before. My gripe is with the idea that this sudo-european civilisation would not only accept but praise Japanese cuisine like it was the second coming. Don't get me wrong I like Japanese food, and try to make it myself at times, however, even fifty years ago if I made something like that it might be rejected out of hand. And it's not just Japanese food, Green Chili is a staple food here in New Mexico, I doubt most who read this would even know what I'm talking about, but the idea of bringing that dish to a pre-Columbian Exchange Europe and assuming people would just like it like I do is ridiculous.
3. This is a personal gripe, I would not eat food that
I know had parasites in it. If it's not life or death and even it you could get them out easily, AND EVEN if you boil it so the eggs and small ones die,
I would not eat it. It's not just the worms and eggs, it's also their shit. Someone's disappointment would not sway me, I would just say, "I sorry, this happens sometimes, maybe next time." because a little disappointment now is still MUCH better than risking everyone's health. But I know he has a magic power that tells him if food is bad or not, which would be convenient, but I would still stay away from it just because it's such a gross idea.