As seen in the log's: denied RWX mmap of <anonymous mapping> by /usr/lib64/plexmediaserver/Plex Script Host A workaround was to create PaX markings and add -m to the binary.
Submitted fix: https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=7074326a1d2480b2f0c20d0562eb009f5325d2cc Please confirm that it is working for you.
Thank you much, the new ebuild works on an amd64 hardened box just fine.