I think USE-less iptables wrongly depends on kernel sources (I believe due to linux-info eclass). The ebuild itself only wants sources with imq or l7filter USE-flags and I used to have it on VPS system with no kernel sources. Now it insists on installing kernel sources which I'm reluctant to waste space on... Reproducible: Always
*** This bug has been marked as a duplicate of bug 120233 ***
If it's wontfix for linux-info eclass, I'd think that iptables shouldn't inherit it...
The inherit is needed and can't be conditional on USE flags.
It's not up to me to decide, all I know is that linux-sources aren't needed and anything but fixing it either in ebuild or eclass is just a workaround. I *will* work around it and I won't insist on fixing it in tree, but I *will* consider it a bug ;-)