How could they let this happen? How exactly did this happen? Were they hacked?
If I'm not mistaken, there was no direct hacking involved in that particular incident rather some crafty people were able to connect certain data to passport numbers of registered voters because of the flaws in the design of the system itself.
And this is the problem, the blockchain technology is here to make our lives easy, but if people who don't understand it at all try to use it, then it will have tons of vulnerabilities... they should hire experts to develop the voting system, and not leave it the normal programmers.
I even think this project should be done by vitalik buterin, that would be the right way.