The TE situation in Washington is messed up. Reed's brain//body is entirely broken, but despite signing an extension in 2016 he's the 3rd most expensive TE in the league!
What I'm getting at is that they actually need Davis. They can't rely on Reed, they have no one else and Davis gives them stater caliber reps for a fraction of the cost.
Finally I'd add trading with Washington it hella-tough. Look at the Trent Williams situation. He wants out, other teams GMs have been calling and their GM, Bruce Allen, just doesn't want to trade at all. They are 1-5, just canned their coach and are definitely in a rebuild, but they refuse to take trade offers for a 31 year old, often injured tackle who is the ONLY current hold out remaining.
Anyway, it's a nice idea, but won't happen. Just too many things that would mess with this trade.