When the pet cause is something that affects working conditions at the company, then that "issue" you describe is simply expecting the company to follow labor laws.

Workers have the right to organize with other workers and advocate for change in their working conditions without retribution from the company.

You're misrepresenting the facts. The newspiece states that the activists were fired for tracking and doxxing colleagues that they seemed reactionaries. This sort of abuse is hardly defensible.

    the issue is practicing political activism 
    for your own pet cause in the workplace on 
    company time