Yeah, Eugene has become a badass. Nothing like Kirkman's knack for subtle character development.

"I lied to everyone about who I am! I'm just a science teacher!"
"Making bullets is wrong, I don't want to kill anyone!"
"I've decided that in order to save lives you have to take others."
"You can cut my balls off but I won't talk!"

It's like he slowly changed right in front of us.

 

Why doen't Rick just stop by the Munitions Factory and take the equipment? Or, clear it and station, like 20 soldiers there?

 

I'm sure Rick fears that Negan already stationed snipers in the area to pick him off with Negan suspecting that this is an area that Rick would most likely visit again. So Rick probably realizes that more planning about securing the area will be required which they currently can not do until they regroup and rally.