I point out that volcanoes are full of lava! And poisonous smoke! And the magma chambers are not that deep!
Uncle points out that Sneffels was last active in AD 1200, so it is "probably" safe. Only "probably"? And Iceland is on the gap between two major continental plates, so who knows how deep the fissures go?
Should I remind him that humans cannot survive the heat and pressure deep underground? Or remind him of the dozen other reasons why this would be fatal? Or just follow him to our deaths? Or do something else?