I read through the whole thread, and all of your responses, and I see one thing that has not been mentioned: Agency.
You had no agency in "cheeks" asking if the man with you was your dad.
You have no agency in the actions your brother is taking on your behalf.
Rest assured, Cheeks will lose his job. I have friends who are in both Management and Training at Goodwill, and one strike is enough to put you on the black list. They aren't hiring the cream of the crop at Goodwill. They are giving people an opportunity to pull themselves out of whatever hole they are in, by providing free job training, counseling, and other services people need to get back on their feet. So they have a very quick fuse. If you cause any sort of problem, you are out. There is always another person waiting behind you for the opportunity, and Goodwill needs to get people through the system and trained so they become productive employees, as opposed to unproductive trainees.
This man will now lose access to that opportunity permanently, because there was a claim made against him.
Goodwill will do the right thing and talk to your brother about the experience, and will do most of this verbally instead of in a written format, because it is a discovery process.
However all of these actions and activities are being taken on your behalf, because your brother has robbed you of your agency in this situation.
You chose to simply ignore Cheek's request. That was you taking the action you felt was appropriate to the situation.
I have no horse in this race, or have a position to defend in this situation. I'm just stating the facts in a way that might encourage you to take an active role - to regain your agency - in this situation.
I equate your brother taking action on your behalf as equally as demeaning to you as Cheeks' initial comment hitting on you. These are two men who have acted in their own interest, with you as the fulcrum.
Personally, I would not be happy in that place. I would feel used. That's my $0.02.