I really feel for HF customers but I too don't understand why so many people actually think a BTC refund is even possible. Their claim that they would give full BTC refunds actually was one of the reasons I decided not to order from HF because it sounded scammy since there's simply no way they could guarantee it with BTC's volatility.
Sure they could guarantee it, and in fact they did just that.
All they had to do to make it possible was hold enough BTC to cover all of their BTC-denominated liabilities. Having guaranteed those refunds in BTC, not doing so would be irresponsible at best, and criminal at worst.
So you believed that they would be able to design and manufacture everything without touching any of the pre-order funds?