Not quite. Pure nitrogen forms an inert dimer with a very strong bond. The nitrogen that goes boom is the energy released by forming such a bond when you libera

Not quite. Pure nitrogen forms an inert dimer with a very strong bond. The nitrogen that goes boom is the energy released by forming such a bond when you liberate nitrogen from complexes with other things than single nitrogen atoms. Like hydrogen and carbon and maybe oxygen. But this stuff in the article is pure nitrogen, and isn't a dimer, and certainly isn't inert (it decayed back to the dimer when pressure was released). It'd be a crappy explosive (needs to be kept in a diamond anvil cell...) but it would have released the energy used to form it. In theory there are other allotropes, like octaazacubane (N8) that might be more stable and would be frighteningly efficient explosives.