Apparent lack of activity does not always indicate the member has died, and it would be premature to make such an assumption without certain proof.
I have had more than one case where a PM has been apparently inactive for years, but was quick enough to attend to a TL request, indicating they were at least monitoring their emails for WT.
If a profile manager is inactive for some time, and you have followed the required contact steps with no response from them, it then is time to file an unresponsive profile manager form. Not a death of a member form.