"Broom is," he says.
His hindbrain knows that this is a situation where he needs to think very fast to avoid punishment rather than appearing unthreateningly stupid.
Broom removes the other ring. Not the invisibility ring, the ring that conceals his alignment and his thoughts. He knows that powerful wizards can read thoughts in general and his thoughts in particular.
Wink right eye if I should try to explain, left eye if you explain, he thinks at the security guard.