According to Google, they found out about it in June, and I think it's fair to assume this was shared with Intel shortly after. From the moment it's shared with Intel, it's fair game. It's up to him to setup the company in such a way that important information like this gets to him quickly.

Even if he knew about it, if it was more than 6 months in advance and he follows all the legally-mandated protocols for setting up a regulated stock trade, isn't he safe?

The marvel is that somehow the news was kept from hitting the media until he had finished his trade, and then was revealed immediately after the transaction was complete. I wonder how that coincidence happened.

The SEC would need to be able to show that Krzanich initiated that rather large selloff based on this inside, privileged info. Given the short document retention policies in place at most companies, this would presumably prove pretty difficult.