Why didn't Time blacklist the "devoters" by their IPs (or respective small subnets) ? They couldn't be that incompetent. So it's reasonable to assume that the blacklisting wasn't working, which means the hack must've been mounted in a distributed fashion, which in turn implies it was ran over a botnet of some kind. Hmm ..
As the article points out, they didn't even write the poll correctly: Two pairs of candidates shared the same ID. That means that if Oprah Winfrey got the highest score, then Ratan Tata would also get the highest score. If the competition was not hacked, these pairs might have done quite well, since they'd get the combined votes of the two candidates.
If TIME couldn't be bothered to get the poll right in the first place, it's not surprising that they barely tried to fix the hacking.
After it was obvious they were being gamed, they did just that. For IPv4.
Then someone discovered there were no blacklisting going on for IPv6 requests and ran amok, effectively being able to throw out around 30k votes a minute without a botnet. After that the poll pretty much looked exactly like whatever whoever gamed it decided it should be.