Note that the article is by an organization that is NOT the AAU and, in fact, is highly critical of its elitism. This is an organization that is reflecting how it *wants* the AAU to change in how it evaluates new potential members. However, the AAU has shown to be essentially the opposite (as evidenced by its removal of Nebraska, which then led to the preemptive resignation of Syracuse) - it's becoming more elitist than ever.
So, the sheer size of the school is irrelevant with respect to UConn's AAU prospects. However, the larger issue for UConn is that there are a number of schools that are stronger in areas that the AAU loves (i.e. high profile medical and STEM research), such as Miami, that still aren't members and would be perceived to be higher on the pecking order. With the AAU is growing at a truly glacial pace (only 4 schools added in this millennium with 3 schools removed, for a net change of only 1 additional member in the past 15 years), that's a VERY large barrier. UConn can continue to improve academically, but the AAU is completely about graduate research prestige (as opposed to undergrad rankings, where UConn has been making most of its strides) and UConn has several schools in front of them that they would need to leapfrog. I don't think a lot of people are quite understanding just how closed and elitist the AAU is right now - they make the power conferences look like open-invite meritocracies by comparison. UConn's power conference invite prospects essentially have to assume that an AAU invite isn't coming (as further power conference realignment is much more likely than the AAU expanding its ranks dramatically, if at all).