Wow! That's an archaic view. Maybe 20 years ago this was a relevant distinction but there's no basis to suggest an institution that has been functioning as a university for many years now wouldn't meet the standards of older institutions and things like the RAE bear this out. As someone said, an "ex-poly" can be outstanding in one particular area, but bad in others. Similarly, so can a traditional university.
Still, the universities are completely at liberty to make these decisions and distinctions, even if they are slightly out of date.Obviously, they are only trying to uphold their own good reputation even if the criteria is misguided.
That said, they really should make it clear because such distinctions obviously don't exist in Britain so why would anyone from Britain ever imagine the distinction would be made elsewhere? You cant ask about something if you're completely oblivious of what to ask for. I really think in some way this should be brought to their attention, but unfortunately I very much doubt it will help you.