[damoncali]

There may be a real reason for the deadline - internal process, internship program schedules, the hiring manager just wants to get it over with, etc, so it's probably wise not to ignore it completely.

But never, ever, ever, ever give anything resembling loyalty to a big company. It is not a person, and cannot appreciate it, no matter how much you want it to. Until they're paying you, you are free to do as you please, ethically, legally and in every other sense of the word.