Why would I heat the gray water...?

I'm picking up my NTU 2001 2619 tomorrow afternoon and I can't wait! I have read the amazing checklist/guide and there was a plumbing tip that has me stumped. I couldn't find anything else on the forum about this. It appears on Page 92 of the handy-sized guide:

• Add heater to gray water holding tank.

Why?

I plan on doing several little mods during the week, before taking it up to the mountains for the holiday weekend. This isn't on my list, but I'd consider it for next year if anyone can tell me why I want warm gray water.

To keep it from freezing... Important if you are going to use it in very cold weather.

Oh, of course. I don't mind the cold-weather camping but it's the ice and snow towing that keeps me home all winter, so I probably won't need that mod any time soon. Thanks for explaining!

Why not just dump a little RV antifreeze in there? I've done it several times.