On FB, a group member offered this advice, and for me, I think it is a better solution.
If you go into the PDA (proactive driving assist) menu in the dash, and turn off DA (Deceleration assist), It'll stop automatically slowing you down when there's traffic ahead.
The behavior you're describing is not the PCS! When the PCS engages, it'll show alerts on the dash and scream at you, Deceleration assist is the annoying silent partner that works kind of similar but doesn't make any noise or alerts. So duimb that it comes enabled by default