I "shamed" someone into tipping my son

My son is 18 and currently in college now. He's bi and has a boyfriend he's been with for a while. Funny thing is his boyfriend is a kid he used to bully him in elementary school but he ended up moving back into our apartment complex and gave my son back his my chemical romance shirt his sister gave him that he stole from him years ago. He held onto it for like 6 years. We also live in Wyoming so things can be a little anti gay. My son works at IHOP as a server and one of my supervisors son's went to eat there and had my son as his server. I will say the supervisors son is 16. So he is a kid but not only didn't tip my son but left a note that said "I don't tip *slur word*" Which was strange because my supervisor always seemed very open minded. My son took a picture of the ticket and showed me and posted it on Facebook.

My supervisor actually brought up to me that his son had mine as a server. He asked me "Did he tip because I taught him to tip." Since he brought it up and asked I told him what his son wrote on that ticket. He had this mortified look on his face and said he was so sorry. That he must be getting that shit from his mom. I said it's fine. My son was more hurt by the comment than him not tipping. Well my supervisor made his kid come in when my son was working, apologize and give him a $50 tip. Some people in my life see it as me shaming a teenager into a tip. That wasn't what I was trying to do. My supervisor asked. I said the truth. It wasn't in hopes he would tip my kid. Just that he would teach his kid not to be an asshole.