I guess it may be semantics, but I agree that I would have the same expectation. However, I also I think getting fired would be a justified punishment in the situation.

It’d like playing a computer game during free library time at the school when I was a kid; I would expect to be reprimanded, however just outright barring use from the computer during free time would probably be justified.

Releasing open source tools showing off what you can do with your company’s APIs is part of the job description for a devrel (signed: a devrel).