Yeah but then those particles reform or get ingested by insects which bloat and then you’ve got some sort of critical mass to form a body again

Yea that is still a concern if entombed. There ARE bugs and shit in there too I guess we gotta seal in concrete, and store in the Permafrost somewhere secret. Go with the Jason Vorhees Protocols. Worse case, Humanities first 'One-Way' trip to the sun