OK, just to throw the discussion open a bit more, ( yes I know we are at a safe computer desk with a cup of tea, biscuits etc etc
)
7500 or fake a problem, what would be the best get out?
I would suspect the hijackers may be inquisitive about squawk/radio changes, but maybe a tail twitch, or power reduction thrown in might give the impression a helicopter isn't a good idea. Maybe start flying out to sea?
How do you know they aren't going to do something once you've dropped them off anyway?