They're not, but range rover actually published an aerodynamic study in SAE mobilus recently. They mention the door handles as part of the product design vision and offhandedly mention it's one of multiple changes that help ensure the flows coming off the front arches don't break up as they move down. They don't bother to single it out though, or even give numbers for the effect of the group (unlike more significant improvements).
They’re also selling a massive vehicle which was designed for macho aesthetics rather than performance. Bragging about minor aerodynamic tweaks is how they convince buyers that it’s okay to spend even more money to take the edge off of that fashion decision. It’s like the places which brag about their single use plastic using some recycled material because they don’t want to say it’d be even better if you bought something which could be reused many times instead.