This is a simple mod for my SNKRX modloader! All it does is prevent max-level units from appearing in the shop.
Follow the install instructions for the SNKRX modloader. Then, download this repository and drag HideT3Units.zip to the mods directory (C:\Users\<your user>\AppData\Roaming\LOVE\SNKRX\mods). Now, just follow the modloader's launch instructions.