Even loaded for BFI-ATH, it's very doubtful that a performance engineering company would have provided a runway analysis (per
AC 120-91 or equivalent) that limited the Bombardier Global 6000 to rwy 32L.
Strange, I've just run it through APG using the current metar (2100z) and its obstacle limited off
both runways, with 32L giving you 2000lbs more than 14R. So it's quite reasonable that to get to a "comfortable" fuel level they wanted 32.