Mikko Virenius

This WordPress Plugin allows an admin user to add comments even if the comment thread is closed.
Features
<ul>
<li>No options panel</li>
<li>No extra configuration required</li>
</ul>

Admin Can Always Comment

I use this on CSS-Tricks for the obvious reasons. I close comments after a certain amount of time, but as an admin, I want to be able to leave comments whenever I want to. 

Works Great with 4.9.6

This plugin allows an admin user to add comments even if the comment thread is closed.

Kevin Pirnie

This plugin generates the proper security HTTP response headers, attempts to generate a valid Content Security Policy, and sets browser permissions if configured.

Security Header Generator

Excellent

This plugin generates the proper security HTTP response headers to keep your site secured.

Admin Can Always Comment vs Security Header Generator