It makes sense to me. o.O If they're an alien, they wouldn't have a native, intuitive grasp of the language. They would have had to learn it, probably through formal study or analysis, so it would make sense that an alien would have very good grammar.
Dropping by... yeah, that's my experience growing up in a country where English is the universal second language. Our grammar tends to be impeccable by default (non-casual situations.)
no subject
no subject
Tis ironic, indeed.