While the media and the fans are laser focused on the drama unfolding in Davie, there are two overriding factors:
1. He's a talented player. The young man has the size and feet to play the toughest of OL positions, LT. His age and relatively low contract number for that position making him very attractive to teams. The cap hit is low enough that he can be carried and developed, so there is an upside.
2. He's a bad player right now. He has always had low strength, which can be a fatal flaw amongst OL. Less strength is needed at C and LT than the other 3 positions, but it is still needed. He doesn't have it. Lacking power impacts run and pass blocking tremendously. Theoretically, while power can be improved, it's not universally improvable. Realistically, each person has a power cap, and once they reach it, only de minimis gains can be made. At that point they either need to gain mass, or they're finished gaining power. The gains are always achieved before they hit that cap. Guys that improve tend to have a history of improving their power since they entered the NFL. I'm not aware of Marting making huge gains in power since he arrived in Miami last year. It is very possible he has reached his power cap and simply is not strong enough for the NFL. That's something that will prevent him ever becoming a starter and possibly end his NFL career. It is really a big deal.
Sure, he has other issues, perception, dealing with the locker room, being teased, ostricised, disliked by the coaching staff and GM that he threw under the bus, hesitancy by coaches of other teams to ever give him a chance, etc. etc. But at the end of the day, its going to be a calculus that heavily weights those two things. If they think he's a good player now who will become a star, then there will be more than 1 GM/Coach that rolls the dice on the guy. He'll get a 2nd, 3rd, and possibly more chances. If they think that this is as good as he'll get, he may never get another shot in the NFL. By his reaction to his situation he has chosen to label himself not only "lockerroom unfriendly" but also "coach killer" and "GM killer" so it'll have to be the belief that he can become great to earn another shot. He is a smart guy, surely he understands all of this. We can only infer that he thought this was the best route forward for him.
