Actually, why bother? If that user does not contribute any content, no one will ever see their profile (except for you linking it here, that is).
This site is about the information, not the people. It sounds so trite when quoted so much, but it is really true. That user spent a bit of time creating the account and it will amount to exactly nothing.
This entire site is about what people do, not about who they are. If the spammer posted a few questions or answers, I would say "flag one of their posts." But they did not post anything — they did not contribute anything to the site — therefore, for all practical purposes, they do not exist.
I'm not saying the account should not be deleted. I am saying that the effect is so negligible to non-existent, it does not warrant adding a "feature" to fix a virtually non-existent problem. You can always write [email protected] to rid the system of this type of noise.
"Spam" problem solved.