... seriously? If I was told, during a job application, that they'd fire me for what I did in my free time, I'd accuse them of wasting my time, and walk out on the spot.
I've seen plenty of blogs etc run by people who're famously employed by big businesses. They all have disclaimers to the effect of "All content is my responsibility, not BigCorp's. Also, any effects of using this website are your responsibility."
And if you're worried about being sued for one of your phone jockeys giving a bad tip, tack a recorded message onto the start of any call: "our customer representatives do not give financial advice; we are not liable for the performance of your investments" or whatever.
I can't see how liberal use of such disclaimers could be insufficient to cover the business' arse. The "protection from liability" claim in the article seems like just an excuse -- I'd say the intent of their "compliance" policy is to give them an excuse to fire-at-will; no-one can follow all the rules, but you only need enforce them against the peons you don't like.
Well, that or to crush their employees' spirits in the hope of Stockholm Syndrome.