It didn't REALLY make Cena look like he ended the streak. Firstly, if this had been just a normal tag team match, the Shield would have taken the victory as soon as Kane was DQed or the second Daniel Bryan was pinned. They've already beaten a different combination of these guys like two or three times anyway, so even if they managed to pull out a victory here, it wouldn't have made The Shield look weak or anything. We all know the trio are beatable, it's just a matter of pulling it off. Secondly, Roman Reigns got DQed because he was too pumped full of adrenaline and shoved the referee to the mat. Had he not done that, it would have been two on one and the odds of Cena prevailing with those odds is slim to none. There's no guarantee that Ambrose was gonna tap either, he may have made it to the ropes. I also don't recall the commentators making it out like The Shield were finally done for if not for the interference at the end. All I heard was that Michael Cole was saying how Cena got a tainted victory since it was by DQ.
A DQ finish is not anywhere near the same as a pin fall or submission victory. I'd still consider The Shield to be fairly undefeated as a trio.