This is a good point, and something not being widely discussed. I don't think Conor has much for the WW division as a whole but Lawler is one of the more winnable fights for him. Even his RDA fight, until a month or so ago everyone (Conor's camp included) said "he's really more of a lw, and really shouldn't cut to fw" Now he's moving up, but you'll notice it's to fight a guy who isn't all that different from Aldo, who he had like a year to train for.
If I'm him and I beat RDA, I want out too. I don't want to stick around and fight Khabib or Alvarez. At the same time, if he's ever going to make a run up to ww, he doesn't want to wait until someone who is stylistically a bad matchup for him has the chance to take the title.