I will say it once more-- because apparently being post #10 is too far down for most people to read-- You can twink at 70 by not purchasing TWW.
Because you have not turned off your xp, and are instead at the level cap for Dragon Flight, the game does not consider you to be “xp off,” and you are placed in the same pool with others that have xp on. The bracket is lively enough to have multiple games going at any one time.