If you read the full article, it covers the law in California which has three tests. Two of those tests are straightforward (company time and company equipment), but the third (related to the company's business) is less straightforward. My impression as a non-laywer is that the courts will probably take a somewhat narrow view of that third test, but the actual language in the law is pretty vague and some companies are involved in many fields.

EDIT: May be a bit less narrow than I thought. This [1] journal article cites some relevant case law.

[1] https://digital.law.washington.edu/dspace-law/bitstream/hand...

I think he is too dismissive of company time though. Company time is very straightforward only if you work 9-5, but a lot of companies let developers work flexible hours and work from home, which I think makes company time less straight forward. Then when you add on call or emergency work you have to do off hours or on weekends (even once every 6 months) it makes the idea of "company time" even more vague.

and pretty much all developers are salaried so the concept of 9-5 doesn't apply

True, but there's an important caveat that they go over in the article: it must not be "related" to your current company.

If that's Google, Apple, or Microsoft... related is a LOT of topics.

Also say you're a games programmer - better not code up a hobby game in your spare time and sell it.

... and so on.

I recall that as well... Mostly from reading it 90 seconds ago in the linked article ;)

then he saved some people some clicks ;)