He likes the look of nearest neighbor texture sampling, not software rendering.

You can do nearest neighbor in hardware rendering and you can do bilinear in software rendering. Rendering mode and texture sampling are two totally different things.

But if you want to experience GLQuake that looks like software-rendered Quake, that's a simple settings change in your GPU driver, overriding the texture sampling mode. That's literally the only difference. I'm not sure the author is aware that it is a viable option to tweak the hardware rendering this way.