Please keyword both sys-fs/exfat-utils-1.2.4 and sys-fs/fuse-exfat-1.2.4 for ppc. Successfully built and used them (mounted several exfat-formatted usb sticks, and did some file operations on them without problems).
Built and used both exfat-utils and fuse-exfat since 1.2.4 up to 1.27 now on ppc64/32ul. Works just as expected.
keyworded all for ~ppc (tested by ernsteiswuerfel)