Usually people making your argument also say that private corporations can and should moderate speech. Do you support that? If so, then why do you disagree with workplaces banning topics?
Corporations setting workplace rules have no impact on your freedoms. You're free to work there or quit, or suffer the consequences of breaking their rules.
How do you decide this? Your intuition? The clothes someone is using? The way his talk?
Consider the fact that you cannot legally offer a service or a fee to terrorist groups (however that may be defined), money launderers, industries from countries under sanctions... the list goes on.
These limitations are political in nature and could be revised, expanded, or eschewed via political action. But even if they were all eliminated, this would not constitute a "depoliticization" of trade: such an action could be characterized variously as libertarian, free-market, laissez-faire, or something of that nature but it would nevertheless be explicitly political.
no it's not - you're just offering a service for a fee. As long as the service is not illegal, and you're not under-charging (which can be considered a political donation), then it's apolitical.
Deliberately choosing not to conduct business with a certain group because of their political ideology, on the other hand, _is_ a political action.