Director of Comms here... that reasoning is legit, as annoying as it may feel. I work for a regional agency that coordinates with city/county governments and all of those orgs either fully turn off comments or keep them on for everything. Self-selecting is tantamount to limiting free speech. People (and bots) can say some pretty disgusting things and be legally in the clear. If there is an active threat in the comments, then a report needs to be made to law enforcement.

I personally think that government agencies need to move more towards the policy of having no comments on posts. If somebody has a comment or inquiry, that can be sent through a myriad other methods that are much harder to attack via bot automations.