Don’t overanalyze. What they’re basically saying is that if they named anything after Hitler, it would be something unimpressive.
Cheese is no big deal (and is it ever “named after anybody”?), and in most cases, it stinks, more than anything else (think Limburger, Gorgonzola, etc.).
I agree, the joke doesn’t make any sense. Cheese seems as fancy as herring, and only a little less so then brandy. And while rats eat cheese, do animals associated with Napoleon drink brandy?
Well, it takes place in Nazi-occupied Poland. I’d imagine someone making a joke about Hitler would end up with a knock on the door in the middle of the night. The joke itself might be lame, but even a veiled insult of Hitler would have been the highest order of political defiance.
Bismark got a little plump in his old age, but he wasn’t really remarkably fat even then, and I don’t know of any story or tradition of Napoleon being a drunk, he was famous for his crazy work-ethic and conquering Europe, which doesn’t really seem like something you could do why sloshed.