Its intentional too. Rand specifically choose the name SEOMoz to benefit from the brand confusion.
From the horse's mouth (Mixergy interview):
"Andrew: What does SEOmoz mean?
Rand: When we started up, we were looking for a name that was short. That had the word SEO in there so that people would know what the blog was about. And, I was a big fan of the Mozilla Foundation, with DMoz and ChefMoz. What was the other ones that they were doing at the time? There was, like, MapMoz, there was a bunch of them at the time that were coming out. That were based around this open source, weird transparent.
[...]
So, that was SEOmoz, was taking SEO and combining it with the moz ethos. There you go."