I don't see how Valve backs the racist flag. They back the game, specifically because it has been banned by Apple. But I don't see any sentiment toward specifically agreeing with the flag and all its meaning.
Right, but they run the risk that the kind of people who are upset with Apple not because Apple have made a general boneheaded move but who are specifically exercised because Apple has removed their flag, will now see Valve as some kind of hero and start acting like Valve is on their side.
While valve may see themselves as supporting free speech advocates, they're also, incidentally and presumably (hopefully) unintentionally, pandering to, and risk validating, racist bigots.
They aren't. The GP is wrong. That's like saying that a historical museum is implicitly backing a racist flag by having one in their civil war exhibit they are promoting this month.
There is nothing racist about promoting a game that uses 'a racist flag' in the correct context. In this case, a historical one.
I don't see how Valve backs the racist flag. They back the game, specifically because it has been banned by Apple. But I don't see any sentiment toward specifically agreeing with the flag and all its meaning.