I don't think California is the relevant jurisdiction here.

The quote from ZeniMax in the article is "With the start of the trial of our case in Federal District Court in Dallas [...]"

Carmack lives and works in Texas. In fact I think (though I don't have a citation for it) Carmack's choice to stay in Texas is the reason Oculus has a Dallas office. Of course Oculus and Facebook headquarters are in California. ZeniMax headquarters (according to Wikipedia) are in Maryland.