MSNBC and other networks made a big deal about the arrest - and no wonder why. It was not just because of the Astro and AR-15. It was also because the guy also apparently is police buff who had various police scanners in the vehicle, had several guns, had books on sniping, and as it turns out, he was a military firearms instructor.
Many of these trait match in a patchwork manner what many of the profilers have been saying. The guy is very interested in police stuff. He had been in the military and was very familiar with firearms such as the AR-15, the civilian counterpart to the M-16 about which he probably gave instruction. Add to that the suggestion that the guy would likely own many firearms, was male, and did have an Astro van and it looks like they had a good candidate for the sniper.
CNN announced that they have already tested his AR and found out that it was not the weapon used in the shootings. Assuming he isn't the sniper, this would just go to show that it is possible to find matches for the suggested criteria and those matches not be correct. The information is sufficiently vague to make such a match without being able to make it as the expense of being completely exclusionary to folks who are not the sniper.