That said... I'm quite sure there isn't a lot of traffic to these pages anyway. The question to ask is - am I going to lose customer by not being available on an iPhone? People will already have decided if they're going to come or not, they don't need the site to convince them. If their friends go or if it has good buzz they will, otherwise they won't. The website is, I think, just an item on a checklist - you have to have it but it doesn't really matter if it's good (or googleable) or not.
For the rest, it's a cost/benefit thing I think. The people who design the flyers (which are an important promotion tool) can easily, quickly and cheaply make a flash website from the flyer design. These things are one-off, they rotate every week, requiring someone who does all the tech frills is expensive and makes the turnaround time longer.
(PS no average iPhone user is going to think 'I'm not welcome here', they'll just think 'hmm it doesn't work, let me try at home tonight').