Harry will always be son of the monarch and then brother of the monarch. He will always be Diana’s son. It’s not factually true that they are ordinary citizens bc Harry can’t escape the circumstances of his birth however much he would like to sometimes.
No one has claimed they are ordinary citizens, they are private citizens at their request, KC is reiterating that request in his statement.
Also, it makes Charles look rather snarky towards his own son and the parents of his grandchildren, which is never a good look. Kings should appear to be above such things; especially when they are head of the C of E.
The statement wasn’t to appease his son, KC was acting as HOS and informing the government, the military and the lieutenants of their position due to the Sussexes promoting themselves as returning to the royal fold.
Also, by laying out a statement which is as rigid as this one, it sets out battle lines that simple weren’t there before. If they weren’t worried about a rival court then they wouldn’t have had to issue a statement about it, so it makes BP look rather threatened and weak. Nor does it leave much room for reconciliation.
There are no battle lines, private citizens cannot form a royal court as much as they may try, the concern from the Palace isn’t about rivalry it’s about being clear that they represent only themselves and no public money should be used for their private endeavours, hence the statement, there is a danger that due to the confusion the Sussexes have caused public funds would be used for their private citizen appearances, to quote Rebecca English:
It comes after sources close to the couple repeatedly briefed select media about plans for their new life back in Britain.
They include a resumption of public engagements with the media invited to attend. Some of the couple's friends have even boasted that Harry has finally secured the 'half-in, half-out' deal he always wanted – with the freedom to mine lucrative commercial opportunities while undertaking limited official duties by the 'back door
And he makes clear that Harry and Meghan's public appearances should not be treated as royal engagements and no public money should be spent on them