A 17" MacBook Pro battery contains 95 watt hours = 342 kilojoules. Effectively using the battery as a weapon would require some creativity, but the battery contains almost 30 times as much energy as the bullet. And lithium ion batteries are known to explode in extreme circumstances.
But the point I would like to make is that it is inappropriate to make important decisions on vocabulary. Is an unused bullet any more of an "explosive" than a laptop battery? Is a long piece of broken glass a "blade over 3 inches"? These screening guidelines are simply guidelines, to be used in context. Should you allow someone to take live ammunition on a plan? Of course not. But when we expect customs officers to strongly interrogate someone who has already landed about a travel souvenir, the terrorists have already won.