However, if they are regularly, (such as weekly), meeting with the White House to talk strategy for the coming week, they are endorsing a candidate, by carrying out the administrations wishes.
Media Matters | Sources | David Brock | The Daily Caller
Meeting with the White House isn't "campaigning", nor is it not allowed by 501c3 laws.
why was the aca denied their status then?
I explained that already. They were denied 501c4 status because their program specifically trained operatives for a single party - and that's all they did.
MediaMatters is esentially a blog site. Everyone can view it, and receive the "education" they claim to do. That's the difference.
Did you know that PNAC is a 501c3 as well?