It is just as obsurd to have a username with white space as it is to have one 46 characters long (45 is just fine :)
You can't message someone with white space in there username, therefore, it is a usless user name that goes beyond hiding identity. That username is unreachable by the means set forth by this site and is therefore bad.
It is just as bad to have white space in the username here as it is to spam or post to USENET with a fake email address.
Enough said.