Walmart using a Arms Dealer to spy on a workers union! Likely more is happening in other companies so here are some suggestions for unions that think they are being spied on:
Independent WiFi infrastructure:
Piratebox, a small access point that runs its own internet type services. No internet needed.
Features are: sharing files, real-time chat, forum, streaming multimedia over UPNP/DLNA.
Advanced info: SSH Management, Linux kernel (and BATMAN-Adv mesh protocol, optional).
TL-MR3040 has a builtin battery.https://piratebox.cc/start
Sharing files between users with CD's, USB sticks and SD Cards.
Snail Mail for sending files using a old school post network.
Encrypted Email:https://protonmail.com/https://www.neomailbox.com/ https://www.hushmail.com
Standard email with https://www.mozilla.org/en-US/thunderbird/
Wickr is encrypted and runs on PC and smartphones.https://wickr.com/
Firechat (internet optional).https://play.google.com/store/apps/details?id=com.opengarden.firechat
Etherpad is a real-time chat program. A HTTPS certificate is recommended.http://etherpad.org/
TOR, for PC and smartphones.http://torproject.org/
Burner phones or Dual Sim phones
Serval mesh app for WiFi callinghttp://www.servalproject.org/
Internet filter on work computers:
Likely work will have internet filters, logging, policies, etc... the best options to available to get around are proxy servers, as there are 100,000's in lots of languages, and don't need to install anything.
Another way is you can install TOR browser on a USB stick, and run TOR from this. Don't need to install TOR browser on to your work PC.
Defeating a Arms Dealer spying on your union you are apart of is going to be very hard, but these suggestions should help you and make their life hard. No solution is 100% on both sides.
Note: any WiFi equipment you place at work, you should be aware some WiFi enterprise makers have Radar systems looking for Rogue WiFi Access Points, just something to remember. Good Luck.