The point is that there was no reason not to just contribute to Wiring and take it from there. The nefarious thing is that they took the project and rewrote its history to make it seem as if it was their own work, meanwhile still taking new Wiring development and incorporating it into Arduino, all without credit. So it was about control and ego. I would assume that even some open source licenses were broken.

Also, Banzi wrote this:

https://blog.arduino.cc/2013/07/10/send-in-the-clones/

lamenting this exact thing when it came to people doing it to Arduino.