... I don't know the parents like you do... but they don't seem really 'with' their child. Distant. Meaning, they disregard him? Don't really know him or per his age? Emotions not being met by them? Nor taught to him about how to express himself or his feelings?
He seems, real pent-up/stressed etc.
His needs are not met.
He is a child.
Not an adult.
Maybe they don't know how... to handle a young child?
Or maybe not.
Things like this are either age-related, due to circumstances/home life, parenting, stress.
But regardless, often times, these things are a CULMINATION of things/years.
Unless, at this juncture, his home life has changed. Or the parents relationship.
Try Google searching "6 year old emotional development."
But really, the parents NEEDS to address it and even if that means, taking parenting classes. If they are not understanding their child.