An alternative route to open source?

The ‘retiring script debugger’ post says:

Will Script Debugger become an open-source project? No. Unfortunately, there are portions of the Script Debugger source code we do not have the right to release.

I wonder if this is a large portion of the codebase? It might be feasible to re-write the parts that you don’t have rights to. If that hurdle could be passed, would you be open to open-sourcing?