It depends if the bomb blast is localised or perpetuates itself as it encounters more matter. If it is isolated to only one universe,if the universe resets instantaneously that would mean while matter is being destroyed in this one it is created in another..Initially I thought no universe is connected ,but in Inferno I think Moira in life 10 had a partially burnt notebook from life 3. So assuming they are. if we had just one living Moira at a time like in HoX-Pox you could suppose the window to traverse through a chain reaction to the next universe is too small. With Sinister having numerous Moiras at different stages of development,I'm not so certain ..this is fiction likely with no precedent, but who is to say the bomb blast won't set off a matter collapse via other Moiras into the other universes?.. Maybe it was stopped by some multiversal entity