All this time. Right there. Why wouldn't the Custodians use a disintegrator raygun? That's their job. To isolate or to disinfect the planet from foreign invaders. The black boxes can come later, when they need to capture or hypnotize the gang. But in the meantime, disintegrator guns are lean, mean and efficient instruments in vaporizing 'the enemy'. Zap! Zap! Problem solved. Why wouldn't Bobby snag one after defeating one of them (a hard enough proposition as it is)? Christ. I can't believe this whole time it's been right. fucking. there.

Unbelievably dense writer.