I've successfully run "conditioners" in numerous power steering units over the years. Never had any leaks or latent problems. I put over 100k on a Chevy van after a liberal dose of conditioner to stop the growl.
The Valvoline is definitely not a 100% synthetic fluid such as Royal Purple. I will say the Valvoline product works wonders on a tired system. I noticed even the power brake portion worked significantly better after a Valvoline fluid change in the Ram.
The Caravan was noticeably better after a Valvoline fluid swap, too.
As long as we're on the subject, I notice MOST systems that don't call for regular fluid change work significantly better with a fresh dose. Power steering, hydraulic clutch, and brakes.
Don't forget the headlight fluid, too... ...