Personally I'd probably do it myself if given the chance. You get the ban, you ban who you choose.
If you want to play Jhin and you just got him, I'd say you should either queue with friends, or don't go into ranked.
Disabling a champ in the first few days is probably bad form. If a high level player actually does pick up a new champion faster then you do, that's not something they should be held back from showing off. And you should definitely get the opportunity to play against Jhin in a serious environment where players seriously want to win.
That being said, I'd say just go ahead and allow them to report players but don't do anything about it. Those guys have serious anger and frustration issues that aren't conducive to a healthy environment and if anything, they should probably get sanctioned or whatever just for wasting the time of everyone who checks out those reports.
All in all; Nothing bad happened here. Move along.