I should think that the RF in their strategy discussions, probably listed for themselves the difficult hurdles that might arise in future. Things like, “if we cede them control of branding with an inferred royal connection, then we have no future control over which crazy shiznat they choose to market”. Prince of Wales probably said “look Mummy, while you still grace this earth, will you help me out by making the tough rulings now?”. Being a wise old bird HM likely sees the Sussex Royal ban as a way to at least have the tough bits out of the way for smoother running later on. This is basically a fight to save the RF brand and all the good things it contributes to Great Britain.
Besides why should some jumped-up (and not even from the UK) date of Harry’s be allowed so much power / influence in established traditions in this country? Why should she waltz in, make a baby, and all of a sudden be deemed worthy of claim to anything remotely royal? She has barely contributed to anything royal. Oh and before anyone plays the race card, this would apply to anyone.
Seems to me Megain will get her settlement when the divorce happens, but the RF could change the terms of his trust release at age 40 as well. Similar to other inheritances, if you don’t co-mingle funds, then inheritance is not part of divorce calculations. Lots more legalities in this than we see publicly, and likely poor little privileged Harry is the ultimate danger...way too much decision making power, without the requisite financial and legal smarts to respect his expert advisors.