If there's smoke there's fire. In my view, Occam's razor might indicate that coincidence is unlikely, and that the two major incidents in US on the same day China's market crash suggest it's a state sponsored cyber attack.
Occam's razor calls for an explanation that does not require the unneeded introduction of a new variable. If you need a state sponsored cyber attack as the alternative explanation, the coincidence theory should be preferred.
Cyberattacks originating from China is not a new variable
Sure, but its mere existence in other contexts does not automatically make it the cause of the NYSE etc. glitches. The assumption of causal relationship without any proof is what violates Occam's razor.
(And that map, while pretty, does not proof state sponsored cyber attacks. If I rented myself a $5 VPN account to Russia and then nmap whitehouse.gov, I would appear in that map as an attacker from Russia.)
http://www.zerohedge.com/news/2015-07-08/what-first-world-cy...
Also, you've got Occam's razor around backwards, always a good way to cut yourself in public (Occam's razor resists adding more complexity to the solution without evidence)