Umm, my comment is kind of unrelated to his post tbh, so there's no point to miss.
You stated "It is the moderator's role to remove posts that do not meet our definition of "civil discussion.""
This is objectively false. As a volunteer mod your role is to remove posts that do not meet the community's definition of "civil discussion".
If you were on a pay roll, owned the boards or in the actual employ of those who do and given that power, then it's your definition. But as a volunteer, your definition does not matter against the community's definition. It's like how just because someone being toxic in game thinks their chat was okay doesn't nessecarily mean it was okay, because the community finds it to be toxic.
If posts you're removing are not being downvoted/consistently being reported/contain what most would find offensive/explicitly breaking Riot's rules, you really don't have any reason to remove them, and doing so would be an abuse of your power as a mod.
The fact that this post has gotten some traction indicates that the mod he is speaking of is well known and possibly abusing his/her power, and you should be looking into this.
Of course if the posts that were deleted do meet standards for deletion and this post is a select few who are simply mad about it sure, keep them deleted. But If this guy/woman seems to be a consistent problem, he should be looked into as a mod.