We live in a free society so a staunch Republican can say what they want about the Queen, but I can call a staunch Republican a **** for presuming stuff they’ve got no evidence for.Of course it's on.
I happen to be indifferent towards the royal family but, for example, a staunch republican will and absolutely should be allowed to slate the queen as much as they want, and they would probably have reason for doing so. Take your blinders off.
The facts that she's nominally in charge and you seem to like her absolutely do not make her immune to criticism.
And it's spelled subpoena.
Kaz can say what she wants and the other person can say what he/she wants - it’s how it works.