The problem is that everything is always complicated.
If employees use the company's email system to discuss politics, then the company's email system contains their policy views, which may not be the company's. Then the company gets sued by someone else who gets a copy of those emails and uses the employees' personal views as evidence of the company's official position.
A solution to that would be to have the law be that political discourse can't be used as evidence of policy or intent in a court case. That might be a good solution, but there may not be support for it in the existing law.
The alternative would be to prevent employees from using the company's official channels for their political discussions, to create a brighter line between official and personal speech. Arguing for the second thing is worse -- it has a lot of other problems -- but arguing for the first thing may not be possible under existing law, leaving it as the company's only apparent alternative to avoid liability. What are they supposed to do then?
If employees use the company's email system to discuss politics, then the company's email system contains their policy views, which may not be the company's. Then the company gets sued by someone else who gets a copy of those emails and uses the employees' personal views as evidence of the company's official position.
A solution to that would be to have the law be that political discourse can't be used as evidence of policy or intent in a court case. That might be a good solution, but there may not be support for it in the existing law.
The alternative would be to prevent employees from using the company's official channels for their political discussions, to create a brighter line between official and personal speech. Arguing for the second thing is worse -- it has a lot of other problems -- but arguing for the first thing may not be possible under existing law, leaving it as the company's only apparent alternative to avoid liability. What are they supposed to do then?