From the company's perspective, you'd need at least 2 people doing that, preferably everybody. Bus factor of 1 isn't great, and when the rest of the team already knows Python, the benefits of switching to a language everyone knows is huge.
You're also presupposing Python is inferior to Erlang, which I'm not really going to argue about here, but I think we can all agree that Python isn't so bad that the decision to continue to use Python substantially and negatively impacted the org's ability to succeed.
You're also presupposing Python is inferior to Erlang, which I'm not really going to argue about here, but I think we can all agree that Python isn't so bad that the decision to continue to use Python substantially and negatively impacted the org's ability to succeed.