My guess is 90% of the BTC "dropped" will never get spent, and will forever remain permanently locked in the blockchain.

I'm sorry, and I'm all for bitcoin, but this idea is ridiculous.  What's the average person going to get?  Maybe $5, so 0,011 BTC?  In general, these are fishermen and others who work for low wages, and for many people, their biggest investment is probably some sheep / goats, maybe a cow, etc.  You're going to spam the entire island via SMS letting them know they now have 0.011 BTC?  They're going to laugh at it as if it's just some huge joke, and make fun of the stupid mainlanders while sitting around enjoying dinner and drinks that night.

That's the most likely result.  Trust me, these people aren't abandoning cash for bitcoin any time soon.