If he fights Diaz again, you 100% know it's going to be at 170lbs since Conor has bulked up at this point and wants to be the bigger guy if possible. It's why he's calling out LW fighters to fight at 170...
Diaz at his best is when he's at 155lbs and will be in the best shape for a proper rubber match. If they're going to fight, it needs to be at 155lbs.
If Conor is staying at 170lbs, he needs to either fight Masvidal or someone who is a true 170lbs fighter. I'd like to see Wonderboy as that would be a fun fight. Woodley/Edwards/Maia/Covington/Usman/Chiesa all grapplefuck Conor to death so I doubt those ever happen. The other best options are against RDA and Pettis, who are former career LW fighters who are fighting in the wrong division, so they wouldn't do much for him. Lawler is an ok option, but he's ranked #10 and really wouldn't tell us much about Conor at 170lbs either.
Personally I think he's just playing around at 170lbs hoping for a gifted title shot, or a fight against Masvidal so he can attempt to take his belt. Other than that, he doesn't want anyone else at 170.
Conor is suited for 155lbs, and really needs to establish himself in the division with real contender fights.
Enough playing around, start taking fights and prove your worth if you want that title shot. If you beat all the contenders, there is no way anyone can deny you the title fight.