My suggestion is more general.

I sometimes see a post locked by a moderator that frustrates me. I don't know much about the post locking system, but I don't think it's voted on atm.

I simply propose that users with a silver badge can vote to **lock or unlock** posts with tags that they are knowledgeable about. This would take more burden away from the moderators, and introduce a more democratic procedure to the post locking system. Additionally, silver badge holders should be some of the best users to decide whether a post needs to be locked or not.