It's a unique situation. We have 4 starters on the line becoming free agents at the same time. It's clear that TT wants to use Sitton for a year and then dump him. And he likely tried to trade him for months. This sets up a potential conflict that I doubt we have a comparison for. We've seen the suggestions that the team set up Lane Taylor as the new starter last spring.
As far as the "something occurred", we can scratch that. The entire team would not be ignorant, word would leak out.
The team being worried about future hard feelings is plausible. But I think TT really didn't want Sitton, he wanted to develop his younger and cheaper prospects. That explains it all well enough.