That's mainly because the article is basing on the wrong weight assumption the 9750kg empty weight which I already explained is most doubtful.
Also the size of the plane is often misleading. You get the impression it is large when actually the canopy is smaller than the F-16's. Please note when you compare size against people and trucks in the background, Asians are not as tall as Western people, and in China, they use a lot of small micro and mini trucks and vans like you see in Japan.
We know from one of the recent pictures, we have an AVIC/CAC marked J-10 on the same runaway with the FC-1. Interposing the pictures, the J-10 is about the same length as the FC-1, and we know from official data, the FC-1 is 14.5 meters. The plane isn't bigger than the FC-1.
One has to consider the J-10's role models, the Israeli Lavi and the F-16A. The countries with F-16s politically close to China, not just Pakistan but even countries like Indonesia, Thailand and Venenzuela, all use F-16As. Both the Lavi and the F-16A have empty weights around 7,000kg.
It would be neat if the PLAAF decides to release information about the J-10. You had a chance of that in the last Zhuhai, but even that was aborted at the last moment, with much chagrin from the factory, who has prepared a J-10 for the occassion (new paint, labels and such) as they are very much interested for potential export orders. The PLAAF also pulled the plug from releasing public information on the WS-10A Taihang engine which was expected to be shown in the airshow complete with specs. It is quite clear that the PLAAF and AVIC, the military industrial complex in charge of most aviation projects, do not see eye to eye.