Goob, I think on macOS (and probably Unix in general?) spaces in paths are usually escaped. I think wrapping paths in quotes is more of a Windows thing, but i could be wrong.
In any case, I suggest trying the following command in macOS's Terminal:
/Users/ianbell/Games/Freespace\ Open/faf983761735437183cf57046c9b1bc9/innoextract-1.4-osx
That said, ianvoyager, you may want to give Knossos a try as well, as Nightmare mentioned.
In fact, if you could help me with testing the macOS version of Knossos 0.14.0, that would be great. 0.13.3 is the current version, because there's a macOS-specific issue that I've been trying to help ngld debug and that is blocking 0.14.0 from replacing 0.13.3. I'll move that conversation to PM, though, since it isn't relevant to this topic.