I totally agree with you.
Let’s leave the children out of the political arena unless they want to enter it.
For the most part Malia isn’t getting public attention (that I’m aware of) for being a freshman at Harvard. She garners attention only when she allows herself to be photographed in situations that pique public interest. Kissing the British guy is an example, but as far as I could see the publicity was positive.
Otoh, if Malia chooses to blow smoke rings in a place where she’ll be recorded, she bears responsibility for it. She’s an adult, and she knows she’s a subject of widespread interest.