I don't believe a word of it. More unnamed sources bullshit. When has Mathis ever been to afraid to publicly state something that displeased him?
You don't believe that Trump acted without believing that he needed to consult with anyone once he'd made up his mind?
Isn't acting quickly and decisively one of the man's most distinct character traits, and one for which most of his supporters are praising him?
CEO's don't seek the approval of their subordinates once they've reached what they believe to be the right decision on a course to take to resolve any given issue.
Having said all that, the story of Mattis and others not being consulted prior to the EO being signed is wide spread, and many members of the GOP have personally attested to the fact.
But we all choose to believe what we choose to believe.