Not one team wanted Osweiller on the 53 man roster either....not even Cleveland where they decided to go with a rookie QB.  They thought so badly of Oz that they paid him $16 million NOT to play for them.  But Elway picked up Oz.
If Trevor gets hurt, who would the Bronco fans be excited to see come into the game?  Sloter or Osweiller?  This is Osweiller's 6th year in the NFL.  The entire league knows what he can do and it is nothing much.  This is Sloter's first year in the NFL (after playing 1 year of college football).  And he demonstrated remarkable instincts.  His ceiling is so much higher.  Give the kid a chance rather than go back to the Osweiller. (who is putrid and stinky).  And Sloter on the active roster would have cost less than Os.