Please tell that to MSP.You don't need to refer to or give information concerning an expunged charge when applying and refusal by a person to disclose said information cannot be the sole reason for denial for a permit. If you had the charge expunged before you applied I would contact a lawyer and appeal. It is a violation of Maryland Code. If you got it after then reapply.
The most common reason for disapproval- making false statements on the application.