Support seems to be kind of non-existent
Primer and Primer2 are "traditional" vendor demonstration platforms; some chips in a neat setup that is supposed to attract the interest of "real engineers" who might actually use those chips, thousands at a time, in some consumer product. The idea that a demo platform might be useful on its own, as opposed to just being a sort of digital pheromone, has yet to really catch on with chip vendors. As you say, "support" as seen in the arduino community, is pretty non-existent. (oh, you can probably get support for a product design, and such support can range from incredibly valuable to useless, which is how chips live or die, but that's not really the same thing as we have here.)
This is mostly because such support is really difficult to do. It's a sort of chicken-and-egg problem: if you have enough people with varied levels of expertise and helpfulness, they end up supporting each other. But in order to GET enough people tor each that level, you need to have enough people providing "support" to start with. I don't know how many people that is, but it seems to be more than the average semiconductor company assigns to a particular chip. Look at how many near-equivalents there are for Arduino that haven't quite made it:
Atmel Butterfly, PIC USB Bitwhacker, Coldfire TowerSystem, STM32 Primer and Primer2, mBed...