What a shit article. There's a massive amount of context missing.
7DTD is a game created by The Fun Pimps. Telltale Games bought the rights to produce a console port of the game from TFP. Telltale Games then contracted with Iron Galaxy to produce the port. Telltale Games went bankrupt and it's assets were liquidated, one of those assets was the rights to produce the console port. TFP managed to buy back the rights to the console port, but were unable to get any of the source code for the console port. It took years to get the rights sorted out, and it wasn't cheap.
It's a messed up situation, but console players bought a Playstation 4/XBox One game from Telltale Games, a company that went bankrupt and is defunct, and that sucks. TFP is now starting from scratch to produce a console port for the current generation of consoles and that costs money.
Only illegal if the maternity leave was the reason, and it can be shown to be the reason. Over 200 people were also laid off at the same time. I have no doubt bungie added them because of the maternity leave, but it's gonna be really hard to show in a court of law.