It'd be a fairly major faux pas to release a "non-product" open-source project in a way that smells like a product, but I don't think it's an automatic firing offense in most of big tech, especially if you're just releasing some technical (CLI) tool. It's more of a "stern talking-to" situation.

I'm guessing something more happened here. Maybe someone was displeased with how the author initially responded, or some powerful exec really wanted to make an example out of him (sounds like another group was working on an identically-named official product with the same name?), or they were just looking for an excuse to cut this particular role.