I'm always behind on the Carolla podcast because I just don't have that much time to listen, so I have not heard this yet.
However, I wonder if maybe the memory is a little fuzzy now. If I had time, I'd dig up the interviews where they actually SAID they met at a Black Flag concert. I know about the story, but I wonder, if we can't find quotes, if this was just exposition that was never fact-checked, yet kept finding its way into stories about the band.
The Kretz thing may not be a conflict. They may have gone to hear him play after seeing the ad. Then again, haven't listened to the podcast yet, so I dunno if that makes sense or not.