New response on 2v2 titles:

and as expected, it's a 'no'.

http://forums.worldofwarcraft.com/thread.html?topicId=22418945715&sid=1&pageNo=1#16

Q u o t e:
Greetings all, as promised I have received word back from my inquiry.

For clarification: Those who participate in 2v2 Arena Matches will not be eligible for any title rewards from that bracket. This means that Rival, Duelist, etc... may only be obtained if you qualify on a 3v3 or 5v5 Arena Team.