A student asking if a company is hiring full-time engineers is not naive in the slightest. You're writing purely from the perspective that all companies behave exactly like Twilio. In my experience (granted this was a couple of years ago), many companies at career fairs are sometimes looking only for interns. Some are just there for some advertisement, not hiring but still maintaining a relationship with the company.

With regards to the point about Java, rather than looking at just the language, I would think it's more worthwhile to see what a person has built with the tools they have knowledge of, rather than extrapolating that they are unwilling to learn something new.