Icc is released as two different versions. The non-commercial version is normally a few releases behind of the commercial release. I think this should be reflected in the repository. I think the easiest solution would be to add a separate ebuild dev-lang/icc-nc with it's own SRC_URI1="ftp://download.intel.com/software/products/compilers/downloads/l_cc_p c_${PV}.tar" and depending on the appropriate version of the commercial release in dev-lang/icc ?
Contacted upstream, and they say the commercial and non-commercial versions only differ by their licencing. It is up to the user to follow the proper terms of the license then. Re-open if you see an issue that I don't.
