More Reportable Offense Options?

Situation: So playing a normal game as Kalista(bot lane) and decided to make Mordekaiser (top laner) my oathsworn, as Bard (bottom lane support) saw this he immediately started saying negative things such as "GG Bot Lane", "Great No Harass at all" and other stuff. In a early trade he ended up giving first blood to enemy Thresh and Tristana to which he said something along the lines off "If only we had bonus oath sworn damage", after this he just completely left lane. Roaming enemy jungle and died, went into ally solo lanes against their will, our Mordekaiser and Orianna asked him to leave but he still stayed stealing EXP and giving off kills "helping". Of course this went on until 20 minutes where the team in a 3/1 vote surrendered, Orianna leaving due to Bard being annoying. Throughout the game I kept a positive attitude in chat, I asked in all chat for the enemy team to report Bard which made bard say "For what?". In the post game screen I ended up reporting him for assisting the enemy team, in my description I said everything I pretty much said here but he wasn't necessarily assisting the enemy team, as such this type of ban will most likely not work!! Bard was screwing over the team by what he was doing, you wouldn't be able to report him from what he said in game but our team knew he did not want to help in getting the team a win. So what should I report him for...

tl;dr Bard screwing around, but the situation does not exactly fall under any of the report categories (Also sorry I have no screen shots, I have the game in my match history though but I'm pretty sure I can't post this Summoner's name as that would be defamation, although it would be the truth, which would be a defense to any defamation claims)

P.S Heck I don't even know where to post this... as it will most likely be taken down by Riot if I post it in the wrong category, and I believe this is not just a miscellaneous subject but since there is no other place I will post it there

P.P.S He was even smug enough to say something along the lines of "Summoner Code: Rule 4, Abide by the meta to Kalista's likes or be reported", claiming that he is "breaking the meta" and that I am wanting to report him for that, but that is definitely not the case heck I often play Zyra jungle which is definitely not meta. But this extra message is just a result of me being frustrated!!