Right - the flight crew's goal is NOT to make matters worse. Moving the offending passenger to a more crowded section of the plane doesn't make it better. Even the act of moving him might have set him off. Maybe the OP thinks because mom was in PP seat, people in coach should suffer him, not her. No - that's not the way it works. There are multiple factors to consider. Pleasing the mom is not the only one. Unfortunately, the best solution at the time was to put space between the mom and the offender w/o making things worse for even more people - that meant moving the mom.

I guess she didn't move back, therefore he and his behavior really weren't as repulsive to her as a coach seat That probably summarizes it.