Well, you are arguing that Perkins should be the back up QB and giving your reasons. This was much discussed after PS. I'm not going down that path again. On the official depth chart Perkins is our #3 and will most likely be inactive each week in that role. It doesn't really matter how he could be used if he isn't eligible.
To get him up you would have to deactivate another player. Who? Perkins doesn't play on STs. It's the same reason McClutch isn't playing. He lacks experience and is buried on the depth chart. He doesn't play STs. If we see either player in the lineup then we have serious injury problems like Stafford and/or CK being out. And I don't think we want that.