This is the direct quote from your link: "And later I reported that Grier, running his third Dolphins draft as general manager, worked to talk Ross off his position. I was told by a league source Grier even told Ross he was picking Fitzpatrick and if the owner wanted to fire him, then he could fire him."
Which does not say he threatened to resign. And no, saying something to the effect of: this is the job you hired me to do and this is how I'm going to do it. If you feel that strongly that it should be done another way, fire me (and pay me severance since you are changing your mind on how to run the team) is classic top dog management. If any of my direct reports over the years rolled over without a fight like that, I would have fired them for not being senior and/or having the strength of conviction for the job.
So, you didn't make crap up, but you sure as **** shaped It to fit your narrative.
PS. Also, its reported second hand "I was told by a league source...", which happens all the time to shape narratives -- no one here (other than possibly chambers) has any idea if that actually happened, was a planted story to stick a knife in Griers back, planted by Grier to as a show of strength, or by Ross himself to show how he backs his management team. It could easily be read any of those ways.