Wow who knew this thread would be so full of drama. Reading through all of this, I've seen the comment of "vulnerable design" be brought up multiple times. Most electronics are "vulnerable" to liquid damage, and those that aren't typically make other compromises in their design(i.e.performance, cooling capabilities etc..). This shouldn't even be news to anyone. You talk of the design as vulnerable as if it was designed to prevent such occurrences of user inflicted damage. User inflicted damage is not a component of hardware warranties as it is not the computers fault that you spilled something on it, dropped it, ran it over with a car, or whatever else the case may be.
The OP did several things right and wrong, getting it evaluated was a good idea, as was getting it cleaned. However blatantly lying about what was spilled on the computer to fraudulently restore their warranty is definitely not something that was a good idea. There may be some long term effects of what was spilled, and then when that occurs you will be able to fraud your way into another parts replacement for being deceptive to begin with.
And if you really think that saying "I spilled a tablespoon of water on it", when you actually spilled coffee, is not a lie then you are either stupid, willing to deceive yourself, or just not able to think clearly. Imagine if you were given a sealed container of liquid, told that it was water, then go to take a drink and realize its coffee (w/milk and sugar as you describe), you probably won't be pleased that you were deceived(and what if you were lactose intolerant?).
Sucrose and lactose is corrosive to components on your logic board, that had better be the worlds best computer cleaning, or you will have a failure at some point as a result of corrosion, or even mold build up. I suppose you found a means to your desired ends, and you have clearly demonstrated your moral character or lack thereof. As far as the idea of "people in my position would do the same thing", perhaps.. if they share your moral fortitude.
I hope everything works out with your computer working for many years to come, but if it doesn't, you will find no sympathy here. Your deceitful and purposeful actions may lead to an issue in the long term, and it is those very actions that will be to blame. Cheers