I've been getting along with this HK registered local hiking team for many years.
I'm sure they did not attempt to influence terns' habitat but anyway what they acted did.
I will try to contact the organizers and suggest them not to land on the island. If they insist, not on breeding season.
For the access prohibition, I've known that this island has been prohibited from public access. Not sure whether it's just for the area of the lighthouse and don't know whether it's changed after the lighthouse has changed to auto operation some time ago.
I guess hikers/explorers and birders should not have any conflicts as long as they cherish the nature.