It's moreso envisioning how mass production would be applied to it, than anything.

And that's certainly not true. Zombies in media are generally ridiculous in many ways even if you handwave the actual function of a zombie virus. For the same reasons an AI uprising is simply not remotely scary compared to media portrayals of the idea; we've yet to find or make something similar. A little like saying we're experimenting with planet-glassing lasers because we're experimenting with powerful lasers.

Research is being done on all sorts of much more immediately dangerous stuff, and generally with very good reason.

Trying to envision the process of sustainably farming any of the "zombie" fungi en masse is rather uncomfortable, thank you.

Happy to help friend. Agreed, I love these sorts of questions. They're like logic puzzles, but figuring out the answer usually involves learning something more broadly interesting than "ah, it's that particular sequence of steps to solve it".

XKCD's What If? Articles and books are fantastic for this, if you aren't already aware of them. There's about 160 of em on his site, currently.

Absolute zero just means there's absolutely no heat energy in the material; getting near that can cause weird things to happen in some materials, but it doesn't mean the entire object goes supernaturally rigid. (I think that's sorta what you were picturing, anyway.) Inertia and mass and such aren't changing. Causality too, given we're talking about moving light-years-long sticks instantaneously.