1. Would he be informed of the/a bug(s)? Absolutely. We monitor bug tickets submitted to our team throughout the day. It's a main part of our job.
2. Was there a strict code ownership per individual contributor? No. This team's culture was such that once one contributor's code was committed to the main repository, it is part of the team's responsibility, not just the original contributor. In fact, any kind of don't-touch-my-code attitude was heavily frowned upon, worthy of a warning. I understand other teams may have different cultures.
I was too young to know the office dynamics back then, but in hindsight from more life experiences since then, I now see that he was just a very insecure person. His former colleagues were advancing ahead of him, making 4x his salary, and the last thing he wanted was a young team member outperforming him. This observation itself is a life lesson for me.