That shouldn't even matter. They provided me a bitcoin address, and I paid with bitcoin. I don't care if their payment processor converted it to dollars or not; not my concern. Once the bitcoin leaves my wallet and hits the address that their website or rep provided, that's that. Everything else is an irrelevant internal detail.
If you paid in dollars and they claimed that they don't owe you a dollar refund because they quickly bought a few bushels of coffee beans with your payment, and you're therefore only entitled to refund in coffee beans, would that make sense?
Until a judge rules on this, we can only speculate. I do see both sides of the argument, but frankly, I do think HF have a case here. AFAIK, their products were priced in dollar, not bitcoins. Bitcoins were used to fulfill the dollar amount but the number of bitcoins needed to fulfill that amount would have changed daily. Did you think that was unfair too? Its clear to me this wasnt a barter trade.
Another way to look at it; if you had paid with a bank cheque; would you expect or demand to get that very same paper cheque back? Or just the equivalent dollar amount since that cheque was just a way to supply HF with the dollars it demanded for their product? Maybe that bank cheque was signed by a bank director that became a presidential candidate or whatever, and has become worth much more in the mean time, but thats not HF's problem, or is it?