The rumour is based on a very weak source claiming that they know it is 720p after a play test.
Albert Penellos post says:
"Man these threads crack me up. Well done on the Nickelback gif.
I'm not going to convince anyone differently, but it's funny how people interpret the tweet as confirmation.
First - I don't know the resolution. I don't have more sophisticated tools than anyone else. I watch the game on a nice TV with the XBO set to 1080p for every game, there is no way for me to know what's native vs. upscaled unless I'm told.
Second, if I did know, it wouldn't be my place to say anything.
If the Ryse footage last week showed me anything, it's that you get a much more interesting discussion when you're looking at real footage.
So now I've seen the PS4 footage, and I've seen XBO running live. To me, they both look great.
The resolution will be what it will be. It will be known when Activision wants it to be known. The only thing I was curious about was if the games look different, and based on the assets available to me, they don't.
So I think when XBO footage comes out, and people can compare resolutions, effects, framerate and other things the debate will be more interesting.
All that doesn't come across in Twitter-sized bites."
Many on Gaf believe that it should be no problem to tell a native vs upscaled game just by playing. I'm not sure how many have actually put it to the test on themselves since AA and upscaling can make this difficult to determine without direct comparisons.