> It's similar to saying that Linux could not have become a serious project because of the way Linus communicated in his emails.

Linus being rude was actually contributing for Linux becoming a serious project. Because that changed the quality of the code and the seriousness of the contributions. If you were sloppy or did not do good job, Linus became rude. So there is a correlation, and this is an excellent demonstration how it goes to opposite direction. Whether it was professional or not, it correlated for the quality of the project. For that reason, it is not ad hominem.