If you can convince 51% of the network, then yes.
yeah, the fact that ethereum community was convinced is already a death sentence, because it shows that no principle is sacred. go ahead and try convincing bitcoin community to reverse a transaction, that'll be fun to watch.
So can I make a purchase, receive the goods and then claim a bug?
Reversibility of platform bugs is a good thing, reversibility of contract bugs is basically reversibility of plain transactions, which makes the whole idea of cryptocurrency useless.