Earlier quoted context omitted.
That's not what the Friedman Doctrine is, technically. It is that management should obey moral, ethical, and legal frameworks in the operation of the business for the benefit of its investors; and specifically NOT take actions which are outside of that narrow scope.
Does that include trying to influence moral, ethical, and legal frameworks to the benefit of the investors as well? Because if it does it is kind of a moot point.
If you read, eg, Buffet, he makes the point that a manager donating to a political cause, whether the Heritage Foundation or, God forbid, something as far right as the SPLC, makes that donation with money that otherwise accrues to the shareholders. The manager therefore creates an agency problem, where he might pursue his own interests at the expense of the owners.
If they are aligned, the manager can retain the earnings and create a dividend for the owners, such that they can then make the donation directly. If they are not aligned with the owners, they are redistributing wealth.
I am not surprised that the Left advocates for backdoor wealth redistribution, but I would prefer they be honest about it.