Don't worry -- Bungie keeps your privacy very private, including from Ninjas :-) We're just community members, after all. And in general, we don't see much more than any other member except when it comes to certain aspects of Code of Conduct violations on the public forum.

If you (or any member) report/hide/mute with a reason other than "Meh", and there are enough of those reports to make it to our queue, we see the reason, and then make a "guilty/innocent" decision as to the "charges". The "free text" section? That's not currently something we ninja see, I don't know how/when/if that feature is going to play out in the future. But since it's a field in the data, someone somewhere decided that it could/would be of value to log and use (perhaps as a later feature).