Because the young lady is at a point in life where she's defining her values, away from the parents. She's not running for public office or serving in government. It would be hypocritical to say this is okay but be furious when Barron is criticized. Because we hope she grows up without her parents worldview and if we reward her bad behavior with publicity it sends the wrong message. Is that enough reasons?

Thank you for your reply. Please see my post 26.
Publicity for Malia is a two way street. She shouldn’t act publicly in ways likely to attract attention if she doesn’t want it.
Here’s a for instance. If you’re outdoors after dark, no one can record you blowing smoke rings.
But, you might say, it’s cold in Cambridge after dark. True, and it’s also illegal to smoke indoors in most places. Cambridge smokers are used to freezing their fannies off.