Did GSP say that moving down to 155 would be easier recently? He's put on a lot of muscle over his career. He's older. IVs are banned now. Would seem tough.
And the fights just aren't there. Diaz fight is somewhat marketable as a big money fight even though he already beat him.
If he really wants superfights as Rory said, they just don't seem to be there like they were before or right around the time he retired.
He could go the boxing route where he tries to set up big money catchweight bouts that drain his opponents enough to make it competitive. Which I guess was the though in getting Anderson to 170.
I'm all for a Lawler fight though.