I don't mean to insert myself in some "armchair researcher" discussion, but Leyland Cypress is from the family Cupressaceae, not Pinaceae like the Ponderosa pine.
So how does the Ponderosa pine being edible prove anything about the leyland cypress? They are in the same class of pinopsida, but diverge and have different orders, families, genuses, and species below that.
You'd be better off comparing the leyland cypress to other cypresses than to ponderosa pines for edibility I think.