I think the major reason the Nokia engineers didn't jump ship to Apple/Google is that they did not want to move to another country.

The article is written like it assumes the Nokia HQ was next door to Apple/Google.

There is another type of insider trading: If an engineer had stayed at Nokia but bought a lot of shares in Apple after Apple launched the iPhone, would that still be considered insider trading when the engineer did not have any non-public information about Apple, only in which way the general market was moving?

A lot of people laughed at smart phones in 2007-2010, the market majority did not value them and did not predict Apple's stock would grow.