I don't think they mean long term gross (i.e Titanic, Avatar). Over time that will balance out, as everyone who wants to see it eventually will.
But for the opening weekend, which is the record set by Avengers, there will only be a certain amount of screenings possible in the 72 hour window. Even if it's only 20-30 minutes difference in run time, that could potentially make the difference between it breaking the record and not I suppose.
I think TDKR is definitely set up to make a run at it, but if you are looking at it in the truest logical sense, they may have a valid point. I mean TDKR could open as the 2nd largest opening weekend of all time, and that wouldn't really make a difference in my eyes. It would still qualify as a major success, and bested the previous film in the trilogy, so there is no need to pit the two films against each other. I mean some fanboys are moronic and look at it as a pissing contest (i.e IMDB boards), but I think most industry people are looking at it now in an objective way, since going into 2012 TDKR was by far the more hyped film, but 200.3M is going to be near impossible to beat. Movie writers like those two just enjoy being pundits trying to predict the future I imagine, they simply enjoy the battle, but don't have much of a rooting interest one way or the other. Either way it's enjoyable for them since no matter who wins, it's going to be a win for the industry with the biggest summer numbers ever, and that is what I believe they are likely driving the focus towards.