IIRC, I do think that there was additional context to Martin's situation. It's probably now well known. And that's probably because what created it is likely to be technically a violation of league rules and/or the agreement with the players' union. But Martin, according to some reports at the time, had been all but explicitly promised to be compensated better in the future if he'd take a more team friendly deal after his rookie one (I think it was) expired. The Cowboys, supposedly, dragged their feet for an extra year, maybe two, in extending/renegotiating his contract to do so. So, he held out to force the issue.
I think the difference in Martin's situation was that the winks and nods were obvious and undeniable, but the Cowboys thought they could keep skating by on the informality of it all. These types of things aren't supposed to happen, but probably do all the time. But I think I remember reading that Martin, for all intents and purposes, was promised a big pay day later, if he'd take the lower salary in the moment. It wasn't an implicit understanding, or a strong hint, but a verbal commitment that fell just within the bounds of plausible deniability.
I'm not defending what the Cowboys and/or Martin (supposedly) did but, if the reports were accurate (and I believed them to be at the time), then I understand why Martin held like he did. I still don't like that he did it. The whole thing should never have happened, but it did.