Pushing this from middle position is +EV not because the hands that will call you won't be either huge favorites or coinflips, it is +EV because of the fold equity you have here. M of 6ish-8 is usually the hardest spot to decide whether to push or try to raise. If you raise 2.5bb here and get reraised, what do you do? If you are pushed into? Pushing with an M of 6 - 10 from middle position can be +EV with any hand given the position, the fact that it is KQ just gives us a coinflip vs possible pushing/calling hands such as 9's, 10's, and J's. But yes, you are often going to be behind when called, the aspect that the amount of time you won't be called plus the amount of time you will win when called (which isn't as dismal as you may think, but isn't exactly good by any means) makes this play +EV, not by a huge margin, but +EV nonetheless. You can make arguements for just raising here, and I'm not saying thats not the correct line here, and possibly higher +EV as you can push on any nonthreatning board after perhaps milking some extra chips, or you would have scared off a hand that would have called you pre flop and you would have lost to, but pushing is still +EV.