I think you make a very valid point. In terms of the cost burden, I wonder, though. The cost of trying to do refunds, given the depreciation of the mining hardware, is probably quite substantial (it's not like Giga was just holding the money).
Remember that if the contract is totally cancelled then the amount refunded is issue price LESS all dividends paid to date (the dividends have to be cancelled as well) - as ALL transactions have to be reversed. If mining gear depreciation has outpaced generation of dividends then it was a shitty investment in the first place (as by definition that means investors have made a loss). It's not like block-reward halving, steadily increasing difficulty or technological advances were somehow unexpected is it? I somehow can't see Giga claiming that he either totally failed to understand basic issues about mining OR intentionally sold an investment he expected to make a loss for investors. So how could he claim that somehow at this juncture reversing contracts isn't financially possible - as surely that lets him keep all the profit made from investments that are now refunded at IPO price - total dividends?