I think there is a bit of ignorance about how software is sold in some cases. This is not just some windows or browser application that was sold but it also contained the staff training with a help to procure hardware to run that software and maybe even more. Such systems get closed off from the outside without a way to send telemetry to the public internet (I've seen this before, it is bizarre and hard to deal with). The contract would have some clauses that deal with such situations where you will always have someone on call as the last line of defense if a critical issue happens. Otherwise, the trained teams should have been able to deal with it but could not.