You have nicely summarized. But you have not pondered over, objwctively... 1. Is it not violative of definition? 2. Does it not beg for an alternative explanation? 3. Does it not seek certain pre condition for interaction? Like will mere contact would suffice or some momentum would be required? Text says momentum is required, then how much? It is quite likely that for hypothetical pair of matter antimatter the momentum required is so huge that nothing happens even while they are in decent hit, thus completely violating the very definition.