seabios has: REQUIRED_USE="!amd64? ( !x86? ( binary ) )" DEPEND="!binary? ( sys-power/iasl )" which means it is only possible to build with USE=-binary on amd64/x86 systems. but when i add other keywords like arm or sparc, repoman complains: sys-firmware/seabios/seabios-1.8.2.ebuild: DEPEND: ~arm(default/linux/arm/13.0) ['>=sys-power/iasl-20060912'] sys-firmware/seabios/seabios-1.8.2.ebuild: DEPEND: ~sparc(default/linux/sparc/13.0) ['>=sys-power/iasl-20060912'] this makes no sense as those profiles will never permit USE=amd64 and so can never pull in iasl.
repoman support has been removed per bug 835013. Please file a new bug (or, I suppose, reopen this one) if you feel this check is still applicable to pkgcheck and doesn't already exist.
pkgcheck has RequiredUseDefaults.