If that's the case then the people who told them to "stay in their lane" had a legitimate reason to be defensive. Was it better for the business? Who knows since we are only getting one side of the story from someone patting themselves on the back.

But yes, I would say behaving like an interloper in your org and getting people fired because you deviate from your actual job is highly problematic. After the news gets out about that behavior you can better believe they are going to get stonewalled in their actual role.