Singapore already has all of the infrastructure they need to censor whatever they want (online and offline) and they're perfectly comfortable using it. SOPA/PIPA may change what is "trendy" to censor (Singapore currently focuses on high-profile pornography, I believe, in addition to monitoring and limiting dissent, of course), but that wouldn't be a fundamental change.

Instead, what I'd say is that the example of Singapore is a reason to oppose SOPA/PIPA. Giving a government comprehensive censorship tools will inevitably chill democracy no matter what those tools are "supposed to" be used for.