The EAPI version is too high for the currently stable portage, I looked at the ebuild and can't see a specific reason to set the EAPI that high. Reproducible: Always Steps to Reproduce:
Thanks for the report. EAPI4 is allowed in ~arch packages. Of course, this means that you have to use ~arch portage, but it is generally not supportable to mix arch and ~arch anyway. Sorry for the trouble, but this is a invalid report.