The specification *says* re-solutioning, so if you are saying that they *meant* re-aging, that is a pretty major mistake in the specification. I agree with you that you should be able to re-solution a PH stainless multiple times, I just wanted to verify with others before I submitted a commment...
Does anyone know why section 3.4.3.1 of AMS 2759/3 explicitly states that for PH stainless steels, only one resolution heat treatment is permitted? I don't recall any other specifications mentioning that, and from a metallurgical/microstructural standpoint, I can't think of any detrimental...