I can guarantee you that the post was reported, I did so personally many moons ago. That's why I know first-hand that this Board's moderators are just blatantly choosing to not perform their job.
I think this is more along the lines of the moderators maybe not thinking that post needs it, or possibly it got lost in the queue, etc. Riot's pretty strict about who they hire and keep around, so if the moderator team ignores their duties Riot would have a problem with it.
look forward to the profanity filter
The profanity filter is mainly intended to censor particularly offensive racial slurs and spam links, not general cursing. I agree with you, I think that comment warrants deletion, but I'm not sure censoring the words would have dulled the poster's actions at all.