Or that Axl was TOLD he was paid or, even, Axl didn't even know Pitman was owed money. This is mismanagement.

I'm totally being speculative here, but he is suing AXL and not Guns N' Roses, right?
For work done for engineering and not for touring in 2011.
Perhaps arranging/producing for a new album that never came out? Hence why he was relutant to ask for the money, as in waiting for it to come out. Once the reunion kicked in he noticed, given the history Axl has of erasing past contributions, that all the work would be erased and the chances of him receiving his money without making a big splash would be little to none?

Thats probably the retainer as 2011 was an year without touring (except for rock in Rio if I'm not mistaken)

That is called plastic surgery and a little too much botox on the lips.