Browns apparently were showcasing Osweiler in the preseason
When the Browns bought a second-round pick from the Texans for $16 million and took quarterback Brock Osweiler onto the roster, the Browns immediately tried to trade Osweiler again. Per multiple reports at the time, failure to trade him (with the Browns eating some of his guaranteed salary) would have resulted in an outright release.
But then they realized that the offseason program and training camp requires arms. With Osweiler on the books for $16 million anyway, why not use him?
Use him they did. And they liked him, at least enough to hope someone else would love him. So they propped him up by making him the starter for both preseason games, hopeful that someone would still call with an offer to take Brock off their hands.
Someone still could call; all it takes is one quarterback injury to trigger crazy outcomes like Jay Cutler unretiring. So now that the preseason hay is in the barn, the Browns are opting to keep Osweiler healthy by keeping him out of game action, in the hopes of another Bridgewater-style fluke incident that results in a starter being out for the year.
With most starters poised to play in Week Three, a non-fluke could happen in any of the games to be played through Sunday, resulting in the one phone call that would result in the Browns finally flipping the pancake on Osweiler.