I don't think you can point the finger solely at Johnson for the moral abyss the Girls went through. Remember, Tom Landry & Gil Brandt were the guys who brought Michael Irvin & Nate Newton into the organization.
But knowing what I know about Bob McNair now, he & Jimmy would have been like oil & water. Johnson was a very good coach and a great talent evaluator, but he wouldn't fit in with the Texan organization.
“We’re looking for a coach that...works with great energy and enthusiasm and very positive in his approach.” - Bob McNair