He was guitarist for Kenny Price in the late 70's. Roy Nichols was Merle Haggard's guitarist until he had a stroke in the late eighties, so if he did play for Merle it would have had to been after Roy Nichols left the band.
My Dad worked with Leon and his Dad in the 60's and 70's. I believe Leon's Dad was Kenny Price's guitarist for a time, Leon's band opened for Merle several times in the 70's.
The title of the song is Footlights.