Portage gets its path from the ROOTPATH environment variable instead of PATH. This causes problems on OSX because we never define a ROOTPATH variable. I suggest that we add it to the profile during installation, maybe have it mirror PATH. I came across this while trying to get koules to compile. It was trying to use a program in /usr/X11R6/bin, which wasn't in the path even though it was in my profile's PATH. Setting ROOTPATH=${PATH} fixed the problem for me.
This bug will be fixed by implementation of a MacOS baselayout.
Fixed by new baselayout.