They were tristated because of the way in which the code was so badly written,in fact I don't think anyone had even tried to get it to synthesise and I think they posted it because in works as it is on a behavioural simulation but it wouldnt synthesise at all because of mistakes in the code.
synthesis tools are very sensitive about how they interpret code into hardware for ecample a string of it...then ........if..then leads to very different hardware to a string of if....then....elsif...