There is one and only one question in this case. Why would any pilot request clearance to below the known peak altitudes of stratocone volcanoes in conditions in which those peaks cannot be seen?
You are assuming they were requesting a descent IMC, which is not necessarily the case. Just because you can't see the peaks doesn't mean you're IMC. I fly all the time here (in Indonesia) below the tops of mountains that I can't see, and do it safely.