The decision to open source is not something you can ever backpedal on without serious backlash.
Their primary reason for open-sourcing was quality? I am not arguing that open-sourcing can help improve quality of a code base, but if you have quality problems and need it, you should hire better developers.
Quite frankly, for most things that you need for your codebase, even if you open source, you need to do the thing that you need yourself. Fine, there are exceptions - if you work with open source you can likely get a bigger community, potentially build partners, and do more things - but you can't open source expecting the quality to go up.