I wouldn't be too hard on MF, bui. They would have replaced the bass at no cost to you if they had another one. Unfortunately they don't. The suggestion to work through Fender for a replacement neck was obviously half-baked and wouldn't have worked, but at least they were using some creative thinking. MF originally thought the only damage to the bass was the neck. They don't have another bass, but maybe you could get a new neck. As I said, not a good solution but the only way they could see getting you the bass you want. Failing that, the best they can do is refund every penny of your money which they are also very willing to do - up front.
If you have ever dealt directly with UPS, it is not a simple process to get them to pay for shipping damage. I have twice bought items from private sellers on eBay and had them arrived damaged thanks to UPS. In both cases it was obvious the items were sufficiently well-packaged, but something catastrophic happened while they were in UPS's possession. The private sellers did not want to refund my money until they got their money back from UPS. It took me and the sellers working together for months - literally - to get them their money back and therefore my money back. Yes, the sellers should have refunded my money immediately and then worked out their own settlement with UPS, but it doesn't work that way in real life when the private seller has already spent the money on - oh - their mortgage!
This is a real disappointment for you, bui. But no way is it MF's fault. They ship hundreds, if not thousands, of guitars every day via UPS. UPS never tells MF they are inadequately packaged, they just accept them. MF would replace this bass for you at no charge if they could, but they can't. The best they can do is give you every penny of your money back, which they will gladly do as soon as you put the stuff back in UPS's hands.
It's obviously your decision, bui, whether you will ever deal with MF again. IME they have always done the very best they can for me, and it seems they are doing the very best they can for you, too.