I've never seen Trek Nation, but based on what I do know about Rod Roddenberry, he does not come off as a douche. Aside from Trek Nation, he doesn't really try too cash in on Trek. In fact he's usually very reserved in Trek-related matters. I suspect that he was approached and convinced to do the interviews he's done for the TOS DVDs and TNG blu-rays, rather than seek to do this on his own.
Sorry, Star Trek has its devils, both currently and in the past, but Rod Roddenberry isn't one of them.