Or just coincidence? First and foremost, we're aware of their past spammy behaviour, but as a spam e-mail a few minutes ago shows, they're deliberately doing this, so are well aware of it.
This does sort of explain why so many criminals are flocking to them for domains and hosting - as a reply from them to one of my fellow researchers shows, Register.com simply won't do anything about it unless the court forces them.
The following for example, which is a scam e-mail I received, points to financier.com, which was also registered through register.com;
And this is before we get into the sites on their IP range serving malware (not many at present, but the list is growing).