It may be, if SARS is US-made.
However, a full-blown epidemic will hit the US and Europe much harder than (much younger) China... and may assure China's domination within a couple of years. If China is behind this, it was a really nice idea for a bio-weapon...
But all Chinese leaders are old. Most of them over 60's. For SARS to have the desired effect , all these folks should wear air tight space suits everyday. Otherwise, China may secure world hegemony through SARS but they won't be able to hang around to enjoy the fruits of their triumph.
If Hu Jing-Tao and Jiang Zemin are showing up wearing their own space suits, that might be one of the evidences to confirm your hypothesis.:)
Alternatively, you can surmise that this is the plan hatched by younger Chinese political elites to get rid of older leadership figures and achieve Chinese domination of the world in one swoop.:)