Yeah, it's skewed. They assume nobody's checking their math.
In a way, they're actually right. Very few people are checking their math because very few people are paying attention to them anymore. The Brady Campaign (formerly Handgun Control Inc.) has been rapidly fading from relevancy since Al Gore lost the presidential election in 2000 due in no small part to his stance on gun control. Brady/HCI has lost every major political battle they've been involved in since 2001.
Actually, it's kind of ironic that the beginning of the end for them was also their crowning achievement: the '94 AWB. Not only did that law out them as the liars they are since crime was not demonstrably affected one way or the other by the AWB, but the political backlash of it (the Republican takeover of congress in 1994 was at least partially attributable to the AWB) ensured that many politicians cooled towards them and became less willing to stick their neck out for gun control. By pushing so hard so fast, they helped to turn gun control into a poison issue politically that no one but the most extreme anti-gun politicians from ultra-liberal districts wants to push too hard for. The phrase that comes most readily to mind is "be careful what you wish for, you just might get it."