The 18 week rule doesn't apply to bariatrics - maybe they are making the most of the dates to get more time, but they have 5 surgeons now, working most days, if they could do it sooner I am sure they would. even if you have to wait a bit longer it is well worth the wait to be seen by a great surgeon, team and hospital with specialist bariatric care in a dedicated ward - they are even doing ops at their other private hospitals in order to get the list down - not sure they could do much more really, AND they have closed their list until they have caught up.
The alternative (like I did first time round) was to be seen within the 18 weeks, never meet my surgeon and have crap aftercare. I know which I would rather have now.
Try not to think about list 'fiddling', whilst I am sure you are keen for your op, they will see you. Try to feel blessed that you will be in wonderful hands, and be well looked after.