Generally ad companies want to sell space to the highest bidder that won’t cost them more money than they’d make. They only bow to foreign Nazis when foreign Nazis are the most efficient way to make money, and that is more about bowing to money than bowing to Nazis.
You can never trust a salesman. And ad people are salesmen selling you buying stuff from other people. Politicians are salesmen selling that they should be in charge of you.
As a general rule, Steam itself doesn’t moderate their forums - game forums are moderated by the dev/publisher or whoever they designate, and user communities are moderated by whoever runs that community or whoever they designate, barring content that is actually illegal in the US (like CP) which Steam will actually take action on. Steam will rarely moderate user profiles, but only if it’s extremely egregious.