Especially after seeing "Please note our core systems have not been touched in months."
This absolutely does not fill me with energy and confidence in regards to Slush.
Do you prefer someone braking it every day or two?
It means the system is stable and doesn't need much attention, which is a good thing IMHO
As stated in the email there is a lot of work being done, but probably on a test system and Slush will make it live when its ready and triple-checked, so nothing will be broken on core system