nO he had the right to fuck her if she was wearing a slave costume.
In that scene, she is his property. Property doesn't get to say no.
She was raped by Jabba, Salacious Crumb, Bib Fortuna, Max Rebo and Droopy McCool, Boba Fett, the Gamorrean guards, those droids that were equipped for it, and the fat guy who wrangled the Rancor. The only reason we know the Rancor didn't fuck Leia is that there's no way she'd survive it.