Argv confirmed to me himself that the basis of channel rules is built on reputation. After he found out that the porno link pasted person he banned was Kniht, and unbanned, he did tell me after I asked him that it's about reputation.
I think mostly it's about security and looking out for the users. You said yourself that this Kniht person that pasted the porn url was an op and was unbanned, well it's a pretty common channel rule that ops do not deop, kick or ban other ops, and besides that, it seems to me that if they know the person that is running the script, or pasting the url, or helping in private, then they also believe this person wouldn't do anything malicious to bring harm to an unsuspecting user. They don't know this of every other user on the channel so they can't have just anyone pasting a url to the channel because that's not safe. The same goes for helping in private and running scripts on the channel, it's just something that's reserved for ops and other people they know. The ops have the power to use their own discretion because they are known and trusted and responsible, which is probably why they were given the op status in the first place.
I really don't think it was your place to notify someone that their ban was lifted and they may re-join the channel and you were in the wrong and should have stopped when asked by the op. You're really showing the world here that you're pretty immature by dragging this all here as if anyone here can, or even is willing to do anything about it, or that anyone really cares at all that you feel you were done injustice. It's my opinion that you should probably grow up and start obeying the rules of the channels on which you have no power or just don't join them.