That's assuming you have the link to their post. The profile page only shows the last 5 posts (assuming they are showing them in chronological order)
Showing everything is not viable under those competing goals. So they have settled on:
Show the post when someone has a direct link, but require login to see the discussion Show a limited number of recent posts on a profile, and require login for more
Raising that limit from 6 to 10 would not solve the real complaint: “I cannot see communication from my city.”
They already identify government official accounts. One simple option is to extend the visible timeline for those accounts only—six months or a year of posts—while still keeping discussions behind a login.