Look at the examples given in your own article - they aren't going to translate to this situation. They're talking about contracts involving unique items where simply cancelling the contract can't resolve it. If you buy something and what turns up isn't what you want you can just return it.
Potentially so, but if there was never a contract to exchange money for source code, then there is no performance you'd be entitled to.
It doesn't logically make sense to concurrently argue that you were misled that the software is FOSS and believe that you exchanged money for source code.