I actually offered to pick up support of the CutList extension earlier and inquired about how to go about it, as the EW’s license terms forbid modification of extensions downloaded from there. As you note, this is a special case as the original author, Steve R, has passed away and obviously won’t do any further development or maintenance.
In brief, the reply I got was that the only feasible way would be to create and submit a new, almost identical extension of my own, exploiting the fact that the existing code contains headers that grant permission to reuse or adapt the code provided the original copyright notice is preserved. The relationship between this action and the EW license, which would seem to forbid it, was not explained. That seemed like a bad approach, both on ethical grounds and because it would leave two inconsistent versions in the EW. So, having enough else to do, I dropped the idea.