I can’t understand why anyone would consider there was any alternative considered given previous precedent of inclusion at PP funeral, PJ and HMQ funeral - all of which were after the OW interview.
Many people have problematic family relationships - if at least one side chooses dignity and not to fuel it - it keeps a door open for later down the road.
I doubt they are too worried about what he will say. These media storms are tomorrows chip paper soon enough but family is for the long haul.
I expect PH is feeling a mix of emotions from hurt, rage, frustration, loss and loneliness with regards to his DF and DB - and these feelings will be amplified by their silence and disconnection as well as the unresolved grief for his mother which often expresses itself again when we have our own children.