Open sourcing when you're shutting down is only marginally better to not releasing anything.
It means that you didn't believe in open source while you were in business, and are only doing so now to score some points with your customers. There's no guarantee that someone will step up and maintain the project for you.
I am glad they open-sourced their code. If you ever wanted to write an autocomplete plugin for SublimeText or VSCode or wondered how to implement a GitHub crawler in Go, their repo is very informative.
It means that you didn't believe in open source while you were in business, and are only doing so now to score some points with your customers. There's no guarantee that someone will step up and maintain the project for you.