Sure there are some big pools that have that kind of hashing power but they dont tend to jump on coins with no trading volume. They also tend to dump right away and there arent even that many sell orders. 0.00000051 is the highest buy order which is very low profit if someone sells at that price and its been sitting at that for quite a while.

I get that the code to calculate hashrate is simple, but you yourself said it was bugged and has been updated so in that case is definitely possible to be wrong. If regular miners arent participating in this coin and all of the hashrate is coming from some private pool, they wont have anyone to sell their coins too. The theory that 7.5 GH/s is coming from some private pool seems unlikely. It really just seems that not many people are mining this and the net hashrate is still wrong.