That's certainly one leading theory, and probably the most likely. However, that happened earlier in the summer, a month or more before he actually shut everything down. There are other possible theories, eg, in his last tweets he lamented about feeling left behind by the progress of open source, or the theory that he planned it all along based on the Poignant Guide's ending.

No matter which of those reasons it was, it's pretty baseless to claim that he took down all of his websites, comics and open source software in a variety of languages including one he created due to some mysterious, unmentioned, irreconcilable beef the Ruby community, especially considering he was one of the most influentual people in defining that community.