Thanks for your views.
No, I don't want to identify the parties involved, I just wanted to get a few other viewpoints on the principle. I did simplify and disguise the situation a bit for the discussion, but it seems most are of the same opinion. That's fine, the bill will be paid.
It's only happened to us once in reverse when someone landed at our airfield with a problem. He got help and no charge. We don't charge any arrivals actually, we just ask for a charitable donation, but our costs are quite low and covered by the resident's fees and so we don't need the income. We feel the spirit of the LAA is less hard nosed commercial than this, and allegedly this aerodrome wants to attract LAA types; how they do it is up to them. Next time if it happens again at ours then perhaps we'll be less generous, and our charity will benefit more.
Thanks for all your replies, they are appreciated.