I do not know if it's intended behaviour, but it's strange for single binary. Maybe engine should link-in FS in that case and put export wrapper to external .so in case server use it? If not, i'm not sure we need single-binary option at all. BTW, static-linking option and ports with custom loaders can be reimplemented in launcher, but it need some refactoring in platform/lib code
SINGLE_BINARY is now removed as an option, but it's possible to disable game_launch compiling for ports, and of course it's automatically disabled for dedicated server.
I don't have anything against STATIC_BINARY, but SINGLE_BINARY option was misleading since renderers and filesystem split, and I don't plan to statically link them just to make single binary mean what it meant before.