Again, you're assuming the kid had the option of yielding so that the drummer could "walk through." Watch the original video that includes the surrounding events.

The kid did have an option to yield: getting on his knees and begging for forgiveness for the crime of appearing at an anti-abortion demonstration as a white Catholic male. Then the drummer (who is a 'professional protestor', by the way) would have had a more dramatic story to sell.

Instead, he smirked.