This sucks and that person should be punished (he will be if he acts like this normally and continuously gets reported), but the rules of the forum prevent us from calling them out on it (called "Name & Shame") and only results in the thread being deleted. If you want to make additional reports against a person you feel a regular post-game report isn't enough for, you can submit a Support Ticket to have someone possibly take a look at the logs and determine if immediate punishment is appropriate. They aren't allowed to tell you if they did, though.
Other than that, there is not much that can be done. These people will always exist, so it's up to the victim to try and mute and report them, and not let what they say bother them (because mute doesn't work in the lobby).
Also, after a game with someone you absolutely don't want to queue again with, delay requeueing for a minute to drastically reduce the chance you queue up at the same time as them and end up grouped in another match. This obviously wasn't your problem, but if it happens you will hate it.