I read it thinking they meant to their cloud platform bills.

But you bring up a good hypothetical regardless. This is why people are not necessarily overjoyed to have folks from other teams sniffing around... if they think you are looking for "inefficiencies" all the more so. Getting laid off isn't the only threat, making their job a lot harder/more unpleasant is also one. Or just being blamed for being bad at their jobs.

To the organizations bottom line, and perhaps to your bosses, it's all the same either way. Hey, you saved money. To your co-workers, obviously not.

You've got to build up trust, that you're looking to make their job more pleasant, not more unpleasant, or non-existent.

It seems like a bit of a stretch that he got anyone fired, but much more likely that they just scaled back on cloud services for that particular project.

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.