There is a sea of difference between your initial statement of "having done all the useful things it could do ages ago, and not finding anything new" and your new statement of wanting conclusive proof that Arecibo has "a unique capability".

The "proof" shows Arecibo was still very useful and finding new things and this disaster will significantly delay research. (As a side note; delays in research can easily mean the death of that research as funding is often time-bound)

Somewhere in this there is a larger story of useful projects not receiving enough funding because they aren't sexy enough.