You can't confine the soloing that John does to anything, llike saying John just works in the Pentatonic scale or something like that.
The style of improvisation at Johns skill level cant just be written off as just the pentatonic scale.
Sure, the pentatonic scale is a large base that provides a lot of landscape for improv and blues playing, but Johns improvisation weaves in and out and up and down the whole fretboard.
All I'm trying to say is you just cant confine his style to one scale. He plays what he feels and thinks sounds right.
Just some thoughts.