This article (and most of the rest of the information I found on the Internet) is referring to solicitation of customers, not solicitation of employees. The few sources I found [1][2] indicate that non-solicitation agreements for employees are very much enforceable, but only if the employee directly reaches out (if the current employee contacts a former coworker about a job, that's legal, and ditto for the former employee's new employer).

[1] http://www.pashalaw.com/legally-poaching-employees-company-a...

[2] http://www.nolo.com/legal-encyclopedia/understanding-nonsoli...