I am not sure I see any grey area. Micah Parsons is not self-representing himself. He is represented by his agent, David Mulugheta. According to Parsons (link):
“In March, I met with Mr. Jones to talk about leadership. Somehow the conversation turned into him talking contract with me. Yes I engaged in a back and forth in regards to what I wanted from my contract, but at no point did I believe this was supposed to be a formal negotiation and I informed Mr. Jones afterward my agent would reach out thinking this would get things done.”
Jerry Jones has not denied that the conversation took place. When asked about any deal with Parsons, Jones stated (
link), paraphrasing, he commonly makes deals with a number, eye contact, and a handshake. I am assuming Jones used the same tactic with Parsons without Mulugheta present.
Previous and current players have self-represented themselves in contract negotiations, such as Richard Sherman and Lamar Jackson, with their clubs. The CBA does not penalize one-on-one negotiations in that regard. It does include language when the player is represented by an agent and is not included in any contractual conversation between the player and their club.