Earlier quoted context omitted.
FHS ( https://en.wikipedia.org/wiki/Filesystem_Hierarchy_Standard )
Can't see how that applies. Does FHS really say anything about the structure underneath /usr/local ? Besides which, the Mac's filesystem isn't FHS in the first place...
If you want to be strict about it, yes: http://refspecs.linuxfoundation.org/FHS_3.0/fhs/ch04s09.html