[Ken Case]

My advice is to upgrade to the latest build (93539), which lets you define how each context maps to your calendar list. It will start out without any calendars mapped, so it won't care what changes you make to them. (It also has a new checkbox in Synchronization Preferences that says whether actions deleted from calendars should be deleted from OmniFocus; you can turn that off to be extra safe, and in fact I believe it's off by default.)

You can then decide which calendars you want your contexts to synchronize to going forward.

Hopefully this will help resolve your problem!