No, being the liasson to the White House is far from being a White House insider. Liassons are specifically left out of The Loop, in fact.
By definition, what you admit to the liasson goes back to the entire FBI...that's how liassons officially work...so Felt was the *last* person who would be told about Nixon's secret tapes.
An article I read once, said that Deep Throat couldn't have worked at the White House because of what he actually got wrong. If it was a true insider, Deep Throat would have had better info on the Executive Office side of things.
Somewhat off topic. Woodward and Bernstein are still milking this thing way too much with their silly press releases today. You know that they have already written their book on this, have it ready for publishing, with multi millions of dollars for the rights.
That is why they refuse to talk about it. They are waiting until it is financially advantageous to them to do it. This is not about protecting sources. They are probably trying to shore up their film rights, and foreign language distribution of their book.