Of course it's our business! William and Harry are going to have to cast around for the money, which will no doubt include giving face time to some less than desirable millionaires and billionaires. This leaves them open to all sorts of accusations, the kind that Charles regularly gets criticised for.
They're also going to put it in the gardens of KP which, last time I checked, is owned for all intents and purposes by the state. I'm gonna go out on a limb and guess that if it's not public money that ends up maintaining this statue then it'll be up to Historic Royal Palaces to do so. HRP is a charity that receives no state subsidy. It would be a real outrage if they had to use their precious funds, intended to maintain and protect our nation's heritage, on this statue.
I do wonder, who's going to do the unveiling? The Queen? Or just William and Harry? Would other members of the family be required to attend? It would look bad if they didn't. Will Charles be there? Will Camilla? This is going to be incredibly awkward and lead to criticism for the RF one way or the other.