...in the scenario that someone complained for example about addressing them with their previous name/surname.
Eh, this sounds like something that would be explained better on Snopes. Did the trainer cite the actual cases?
Surely the lawsuit wouldn't be about calling someone by an obsolete name on its own, it would be about the fact that you revealed that you had broken a data retention law by calling someone by a name you shouldn't know, which is very different. Most such "crazy case" examples don't include how a lawsuit was tossed and/or the argument was unsuccessful in real life, or they misstate what the real case was.
Guess if you had been harvesting data you shouldn't have and then targeting vulnerable people based specifically on the difference between old and new data, and there was a smoking gun (leaked business plans referring to the emotional state of recently divorced people, for example) I could see how that might work. Like to see the real cases, though.