The software does not require it to compile, but requires the /dev/tun and /dev/tap devices to be present to run.  You could have a 3rd party tuntap pkg installed, or use the homebrew version, so I gave the option to exclude it if desired.  (fyi: building homebrew tuntap is safe either way, it will not conflict with a 3rd party until you run the sudo post-install commands in it's caveats)