I would hope so, since it's THEIR hardware it's running on (or in case it's rented, responsible for).
But as long as they don't put anything iffy into the code and leave their political opinions separate from that, they can certainly run their own instance however they please. That's the whole point of Lemmy after all.
I suppose, but the ketchup is a big part of the criminal element here. I just can't imagine that playing well with the seaweed.
Also, I looked it up and apparently in order to make Musubi, the spam is fried in Teriyaki sauce, which, being soy sauce based, probably goes a lot better with nori.