The policy has now been reviewed and we are no longer offering the cat policy. I can assure you though that our venue liaison is a very diligent and hard working individual. If he says the hotel allows cats, then you can take his word for it!
As for the specific issues you raise about health and behaviour;
For health, we will investigate whether this is feasible, however as with any check, it is a 'snapshot', and does not give an absolute guarantee that the animal will be healthy 'on the day'.
Animal behaviour is unlikely to be a problem, we have put in place a heavy disclaimer for a reason, not just to cover ourselves, but to also impress upon the owner their responsibilities (although it should be noted that to suggest to the average furry dog owner that they aren't responsible would probably be taken as something of a serious insult!). We have looked toward other conventions such as Eurofurence where animals have been successfully brought (although it should be noted not in any great number) for many years without incident and do not feel that there is a risk to the public. Dog owners typically know how their dogs react in crowds, or in stressful or new situations, and know how to handle them.
We will of course constantly review this particular policy, but we're confident -based on the experience of other conventions- that there will be no risk to our attendees.