^the situation is a bit more volitile than that, you can't fire a woman for being hormonal
No but you can fire someone for disrupting production and causing delayed shipments. You can fire someone for ignoring a procedure, and you can fire her when she claims "well I couldn't read the sign."
She's gone.
In more technical language the discharge was "due to violation of written procedure resulting in delayed production in excess of $25,000 and disruption of processes from violation of procedures."
To be fair though, I did grab the document that gets viewed by the state and put "laid off due to lack of work" rather than "fired" so she can get unemployment.

Asshole am I, but not a evil asshole.

My boss ok'd that as well so while she's not working, she's not without an income. The only ones who will ever know why she was "fired" will be me, my boss, and the QC manager.
I'd just be reluctant to fire anyone in tough times like these.
Indeed, but on the other hand you can't keep someone on who cost the company 16 hours worth of production time. Times like this you need to go out of your way to be sure you are doing EVERYTHING right so you don't come to management's notice.