I boosted a couple of medals "with myself" on my way to the platinum trophy using a rental copy, namely headshots and melee.
A couple of days later, a really funny thing happened. I was using my alternate account, which had almost the same username as my primary one. Now, of course, the one getting the kills and medals was my primary account. Two days into the boosting session, my secondary account was banned for cheating, while my primary account suffered no infraction at all. It was pretty funny as how asinine the moderators could be. He might as well have tempa-banned my primary account as well.
And, on top of that, my secondary account was able to play games and join sessions without any hitch. The only thing that happened was me getting a message. It was like a moderator on a website saying he is locking a thread but then forgetting to actually lock it.