corrupted officers will not want to see his bitcoins baught at $1200 and now fell at $500, corruption money does come easily, they risk their life for those money, so no bitcoin!
You're missing the point, of course they use Bitcoins, just like any other mean available to them. The error is the assumption of one particular amount of money being used for one particular purpose. If they were that transparent they'd have a hard time hiding their money.
Besides, those businessmen will directly give the officials Bitcoins(in the form of an USB flash disk maybe

) when more people know about it. Offcials don't need to buy Bitcoin themsellves.
The businessmen in China are very much concerned about their way of offering bribes, because if their way of giving bribes is too showy, or not that "approprite", or has the possibility of leaving evidence, most officials will reject, and then the businessmen will lose all the chances.
In China, some Chinese officials are more wealthy than you can imagine. They only accept bribes when they are happy, or when the "gifts" really arouse his interest. How to successfully give bribes has always been a big headache for the businessmen. And Bitcoin is indeed an unparalled tool in this field.