From my sources in the AD - the weight is not the problem. The problem is as follows:
The roof was put in in the 80s when current codes (ADA, Fire, etc.) were not what they are today. If a scoreboard is put in that weighs more than the current scoreboard (or our previous one - that one and this one weigh the same) the roof would have to be brought up to current codes. For that to occur, the building would need to be shutdown for several months, to essentially redo the entire roof, at a cost that a.) would be similar to that of a new arena and b.) would require a shutdown of the PC for such a long time that significant revenue would be lost to the university and the ath dept.
One word: Helium