I'm not sure it's a lack of moral courage that leads people (me included) to say stay out of it. For me its perspective. I see children on a regular basis whose parents ignore them, leave them sat in front of the TV, neglect or abuse them.
Whilst an odd parenting style if a parent is engaged and investing time in their child I don't think you need to get involved. This doesn't sound like a child at risk of harm.
Yup, it's a fine line, but the OP's spidey sense is tingling - that would be enough for me to take some form of action.