I'm going to tell a group of black women to go to the back of the line after they cut to join some friends
Why do you insist they go to the back of the line?
What they did was unfair to the people who got in line before them.
Cutting in line is rude and wrong. No one should be ok with a line cutter.
Are you saying I'm wrong?
No, you are correct. People need to respect those who have waited their turn, and I think you are justified in asking these people, politely, to obey the same rules as everyone else.