If I remembered correctly, rubble only closed off one part of the HQ. One part- the entrance, is extremely dangerous to enter, but is all the less accessible. If I could restore the weapon, then I would have more power than I'd ever dream of. I could continue his plans. Or I could use it for its original purpose-- restoring life. The recreation of the Floette that appeared in legends was proved true, which means I could possibly restore his... but many Pokémon were killed to restore that one, tiny life. Imagine all the lives I'd have to take to restore his life... it's mass murder.