Thanks for forwarding this to us Ben,
Such a flight could well be interpreted as being included in the following flying display definition. "Any flying activity deliberately performed for the purpose of providing an exhibition or entertainment at an advertised event open to the public."
If so, the proposed flight comes under special rules.
Anyone considering accepting this invitation should check out the flying displays regulations and satisfy themselves whether or not the proposed flight would be included, and if so whether they are able to comply with the regulations for flyings displays! Sorry if this is cold water on an otherwise fun event.
Chris