They are protesting the people in the busses, not the busses.
The protesters are angry that there are relatively prosperous individuals in "their" neighborhoods at all; they would rather it be an affordable slum than be priced out.
It sounds to me like the people who gentrified the area are now complaining about getting priced out of "their" neighborhood. I expect the same to start happening in Williamsburg once the yuppies start moving into all of the new condos.
the gentrifiers got gentrified out of williamsburg, and most of BKs western neighborhoods, years ago. average 1 bedroom prices are already at about $3400/month in williamsburg[1].
The protesters are angry that there are relatively prosperous individuals in "their" neighborhoods at all; they would rather it be an affordable slum than be priced out.