Xfinity Stream App For Amazon Fire TV Stick

I was told by a Comcast customer support person that the reason that the Xfinity Stream app isn't on the FireTV App Store is because Comcast can't get a contract with Amazon.  They didn't specify what type of contract, but stated that Comcast has been attempting for a long time.

Question for Comcast staff... What type of contract exactly is it that you need to have to be able to publish the Xfinity Stream App on Amazon's FireTV App Store?  It seems odd that you would need a contract as many people can follow their developer process to publish apps.

Thx