You can sue anyone for whatever you like. Question is, will you win? BTW, I didn't say diapers are causing harm, just that they were wrong brand.
I have full freedom to decide how I want to raise my kids as long as I am not breaking any law. There is no law against using cheap diaper, buying ugly clothes or posting innocuous photos. If you can sue (and win) here, how will you prevent someone suing parent for sending him to soccer game causing injury?
Every parents in the world has done few things that their grown up kids might not like. If you think big brother should interfere than you are the one who needs to leave this world. Parents want freedom, not your diktat.