"Buyer's remorse" is not a new term in the dictionary; in fact it's very old, well known, and has everything to do with this case (wherein reasonable understanding of context is studiously ignored because it precludes grants of outlandish windfalls).
I know you want that to be true because HashFast screwed up so badly, but it's not true. HashFast promised full BTC refunds
for any reason if they were late. They were late, therefore they must offer full BTC refunds. Look up classic "if...then..." logic to understand fully what's going on.