Malaysia to Singapore via China?

Would I be granted the 72 hours visa free transit flying from Johor Bahru (JHB), in Malaysia, to Singapore (SIN) via Guangzhou (CAN)? Obviously the purpose of this trip would be for a weekend trip to Guangzhou, not transit, since JHB and SIN are right next to each other, but it seems to me that I could leave from Malaysia and then take advantage of the visa-free transit. Would this be allowed even though it's obviously just a tourism trip that meets the requirements for visa free transit?