Is there a big enough commercial market for private Python package registries to support an entire company and its staff? Looks like they're hiring for $250k engineers, starting a $26k/year OSS fund, etc. Expenses seem a bit high if this is their first project unless they plan on being acquired?
Continuum has been doing something very similar with Anaconda, and they've been around for over a decade now.
They had contacted a company I had worked for asking them to purchase a license, because apparently somewhere in the company some dev workflow had contacted the conda servers regularly. We never ended up tracing it down as it stopped some weeks before them contacting us, according to our network logs.
In general, you don't resort to such sales tactics unless there is good cause (significant usage, where you as unpaid vendor also have leverage) or you just end up burning potential future customers (as was the case here, as they chose a bad contact point inside the company).