Gargoyle's new font loading directives (propfont, monofont) require the font to be installed in a system location. The installer packages can satisfy this requirement automatically, but the zip file cannot. It is distributed without the Linux Libertine font and with a modified garglk.ini that uses the older fonts.
Ideally the library could still find and load fonts by name if they were placed in either the program directory or the game directory, but this adds another layer of complexity to the process and is not currently implemented.
I thought about retiring the binaries zip, since it's in an odd place at the moment. But I figured the reason people like it is because it offers control over the impact on the OS - no changes to the registry, system files, or file associations. It's not a huge reach to suppose that they also do not care to install new fonts, and the zip file as it stands is suitable for that purpose.