Actually, Singapore and Malaysia predominantly use simplified. In Singapore at least, there is sometimes both simplified and traditional on signs (as well as English, Malay, and Tamil, and many announcements (in the subway, for example) are repeated in all 4 languages), but simplified is what is taught in schools nowadays. At any rate, simplified is just as its name implies, a simplified version based on traditional, so most people who use one can read the other. Taiwan also has its own dialect, Taiwanese.
In any case, Olympia is not wrong in saying that written Chinese is the same in Mandarin and Cantonese, especially since simplified and traditional are essentially the same thing, and there are many words which were not simplified and are the same in both forms. There are certainly people who speak Cantonese and write in simplified, just as there are people who speak Mandarin and write in traditional, even though it might be more common the other way around. The difference between traditional and simplified is certainly more easily understandable/transferable than between some Chinese dialects (and there are hundreds of them), and Cantonese and Mandarin are especially different. (As a fluent Mandarin speaker who grew up hearing my parents speak dialects from Shanghai, Sichuan, as well as Cantonese, I can understand a lot of the first two, but still can't understand most of Cantonese.) I'd be curious to know how fluent Pell is in Chinese though, especially written. Most of the American-born Chinese I know who can speak fluently are not necessarily very literate, simply because it takes years of memorization and usage to become literate at an adult level.
Anyway, sorry to go off on a bit of a tangent. All this is to say that I'm happy that Michelle has become engaged to someone who seems to be very accomplished in his own right. It would certainly be interesting if one or both of them decided to run for office one day! I do hope we'll get to see pictures of the happy couple after they walk down the aisle. Congratulations to them both!