Bear in mind that College Scorecard and Payscale are attempting to describe different things.
College Scorecard’s overall college salary info is 10 years from starting at that college, so generally six years from graduating, and (as you pointed out) only for those who received federal funds. Their salary info by major appears to be captured even sooner, namely 4 years from graduating.
The mid-career salary info reported by PayScale is based on whoever reports, so not restricted to federal funds recipients, and is based on earnings after “10+” years of experience in a field.