He's pretty anxious about food in general, so it actually made a lot of sense.
No it's not. We know for a fact this is not true.
Here's an interesting story (but you can also find ample published literature on it, or even just like... think about how brains work): https://tomstafford.substack.com/p/reasonably-emotional
The vast majority of allergens, on the other hand, are proteins, with the very smallest proteins being on the order of 1 kiloDalton. Large proteins get up into hundreds to thousands of kDa.