If the Faith were their primary motivation, then they'd work for free. I'm not saying they are fake catholics, but there's just something uncatholic about selling the Faith through books, speaker fees, news stories, etc.
Do you work for free?
Taylor has a large family to support. If he cared about money, he could use his PhD to teach at a university. Or he could have remained Episcopalian and been financially comfortable.
At the root of some, not all, of these attacks on Marshall there appears to be a great deal of envy. To those who are green with envy I say, if what he has done is so easy, just do it yourself.