Why are details like the girls boobs or the man's skin color relevant?
To gather support for the girls side, by bringing in controversy, such as the chance that racism and loveual assault was involved.
I agree with the others who've mentioned it. You don't go grabbing a police officer and you don't stick your nose in where it's not needed. Police have enough to deal with when they're called out, they don't need members of the public getting involved and grabbing or threatening them.