I know of some silent keys that are still registered on eQSL.
I know its difficult to handle this information or take action without some proof of the passing.
One Silent Key I'm aware of is VE9ZL.

Maybe use the 'SK' listing in QST? or link to a database at the ARRL or FCC.
One problem is that the call may get re-issued.
So anyway, I don't know what the easy answer is,
unless we treat a silent key as if they are still with us.
73.
KB1UIF Andy Tedds