How is that not how it works? Insects are arthropods. So are crustaceans, including shrimp. Is it because they live on land that makes people squeamish?
"Bugs" is a generic term for everything from insects to arachnids and other things like Pillbugs - a crustacean and close relative of shrimp. Aquatic crustaceans may not typically be included, but the point is the distinction is arbitrary.
Is there any argument to be made that edible crustaceans aren't bugs that doesn't boil down to 'ew gross'? I simply don't see how this is a stretch in any way.
Absolutely. 'Bug' refers to insects (and, more colloquially, some other small invertebrates such as spiders and centipedes). Crustaceans are not insects.
150 years ago Lobster was considered disgusting trash food only eaten by the poorest Americans. This isn't about taste, it's about perception and the availability of meat. The main difference between a Pillbug and a shrimp (in terms of edibility) is the size. Most small bugs don't have enough meat to be worth preparing in a way where it's not obvious you're eating a bug. It's pretty much just aquatic arthropods that can escape the limitations of air breathing to get large enough to be a more appetizing food source.