No ... the PAC-12 Network is an RSN. They serve a larger region than most RSNs (similar to the RSN Big Ten Network) but they are a sports network that concentrates their coverage on affiliated teams within their region.
The point about Longhorn network carriage was in response to the claim that being affiliated with ESPN would give PAC-12 carriage.
I do not know why BTN gets better treatment on DirecTV than any other RSN. Perhaps it is because they were one of the first and they are being treated like a national college sports network instead of a regional with a large region. It sounds like PAC-12 wants the same treatment. So far PAC-12 has failed to achieve their goal.
The Big10 region is bigger both geographically and by population than the Pac 12 region is. Also, since the Big10 schools are in the eastern and central time zones, their games are in prime time for a much larger portion of the natioinal population. So far, the football game involving a PAC 12 school that had the highest television rating was a game involving a Big10 school.
Being the first certainly helped the Big10 network, but higher viewer ratings also brings better treatment by DirecTV. PAC 12 games do not draw large television audiences regardless of on which network they are shown (unless they are against non-conference opponents that do draw well such as Notre Dame, most BIG 10 schools, most Big 12 schools, or most SEC schools).