Thinking you can just dip into being a bit racist for fun when it suits you is actually quite racist regardless of whether you see yourself as a nice guy the rest of the time.
I don't accept that's what they're doing. They're not thinking "ooh go on we'll sing this racist song because it's fun" they're just completely glossing over the meaning of the lyrics.
The scenario you're describing does happen, and occasionally we do see incidents of racism that were supposed to be behind closed doors where the person thought they could get away with it get leaked. This isn't that, these incredibly media trained players were happily live streaming it because they didn't even consider it racist. Now either that's because they're so incredibly racist to the core that they think the lyrics are fine, or they just don't register what the lyrics are actually saying, just like people who teach their kids Oranges and Lemons aren't actually celebrating public executions.