That's true in theory. The Singaporeans I've known and worked with have pretty much all been bilingual in Mandarin and English, often speaking Taiwanese or Cantonese as well. On the down side, their Mandarin, English and probably other languages are each strange.

Despite having grown up in an English environment and having spent most my adult life in Taiwan, communication isn't necessarily that smooth. It's like they just grab words, grammatical particles, and sentence structures willy-nilly from whatever language they feel like, including Malay. It's not just an issue of "Singlish". Even adjusting to standard Mandarin in China is a bit of work for the Singaporean interns I've met in Beijing. As a casual learner of Cantonese and Taiwanese, it's fun crowd to hang out with, though!