Richard III had zero motive for killing the princes, they’d been delegitimized by the Titulus Regius.
Henry VII had the children of Richard’s elder brother relegitimized and the Titulus Regius copies burned (one happened to survive in obscurity and was rediscovered in the past century), so he could (and did) marry their sister, but the princes obviously had a better claim at that point — apart from the fact that he’d already had them killed.
I did mention that the Tudors wrote the stories. I’m a Plantagenet descendant, not the Tudors, the Stuarts or all of the Germans, so I won’t defend the rumors.