Diego Garcia? Part of the British Indian Ocean Territory....... he he he.....well yes it would be an interesting place to visit. Aside from the moral issues of enforced deportation of the Chagos islanders, I would consider carefully if such a visit at my expense would see a profit. For me, its not about undercutting someone else but undercutting myself. That hurts more...... I would take a long, hard look at the bottom line on this and if the sums failed to add up I would turn the trip down.
It was the US who forced them off with the lease agreement. The UK just "Blaired" along. So I'm technically part of the group that did the deportation. If you want to add ethical reasons for not doing things, I'd have to take John Bantin's advice and kill myself. I'd have to skip anything made in China so they can't afford to buy sharks fin (no ipod, phone and even my computer), not buy anything from Germany that originates with a company that predates the 1930s (nazi ties so no Porsche, VW, MB and Audi), then I have to boycott my own country and also Australia (among others) for ill-treatment of indigenous people. Well Australia is not a problem really!
But the list of companies/countries to boycott is really, really long.
Selective reasoning is a wonderful trait for humans to have, no? 
Photographers need to stop whining, no one really cares.....and to say that they are 'nickel and diming' me is an understatement.
So making you buy dinner after illegally bringing me a lens, breaking importation laws, is ok, right?
Does that make me a professional scrounger? 
What Simon (decosnapper) says is absolutely right, holding the line on principle and professional courtesy is an admirable thing. However, I think it's very realistic to say that small jobs like these won't pay the industry standard fee (whatever that is), otherwise they would not be asking for a referral. The reality of the situation is that these sort of jobs are almost tailor made for the competent hobbyist, where perhaps 10-15 years ago, it would've probably been shot by a pro or semi-pro, or not at all due to budget constraints.