It's nothing special about this release, it's just that this is a release. There's normally a trickle of downloads, which wouldn't be worth attacking because you'd be discovered quickly and most of your targets would be newbie users who don't have much coin worth stealing. Attack right at the moment that a new version is released, however, and you end up with your compromised binary distributed to way more people before it's discovered.

Maybe they're attempting to make the peer-to-peer network resistant to partitions caused by what is commonly called the Great Firewall Of China? In that case, they are not crazy to think that would draw adversarial attention.

Mentioned more-than-obliquely here: https://www.reddit.com/r/Bitcoin/comments/4l564f/bitcoin_cor...

(I have not been following this issue in close detail.)

It may not be a matter of the release being particularly special; rather, they might've been tipped off to some insider information or otherwise be aware of some information they felt it'd be best not to describe in detail right now.