some Chinese electricity company must surely realise soon that accepting and holding bitcoin would be a ridiculously successful strategy. Or is that banned?
Apart from the Chinese government's ban on using bitcoin as currency, the utilities (like all major merchants that "accept bitcoin", everywhere) will want to be paid in the national currency, promptly. They certainly do not want to invest in bitcoins; not even Overstock is doing that anymore. ASIC manufacturers and workers will want yuan, too. So the bitcoins corresponding to those expenses will have to be sold at the exchanges anyway.
The Chinese government presumably would be happier if the miners sold their bitcoins in the "Western" exchanges, thus adding to the effective Chinese foreign trade balance.
EDIT: Since we are on the topic, albeit off-topic: it was on news sites recently that some
New England Mississippi electricity company is suing John Garza's GAWminers for a ~300'000 $ unpaid electricity bill.
EDIT2: fixed Mississippi not New England.
Last interview I heard with the CEO of Overstock, he said they still keep a percentage in BTC, so if you know otherwise, be kind and let us know the source...