“Crop sensor” is kind of a bogus concept that originated online… back when we were all shooting film, nobody ever said that a Rolleiflex was a “crop sensor” Linhof, for example. The only thing that counts is the reproduction ratio: 1:1 means that a bug or a transistor or whatever that measures 10mm wide is imaged on your sensor at 10mm wide, never mind what size the sensor is.
You’re thinking correctly, though, in saying that to fit 36mm of film width onto 24-ish mm of sensor width, you need only about 0.67x magnification (don’t get too stirred up about fractional differences because most lenses aren’t marked very exactly anyway.) The only advantage you’d get with a lens that gives you 1:1 magnification would be if you wanted to crop in on a detail on your negative… and most likely all that would give you is bigger grains. It’s more important that you pick a lens with good edge sharpness and good field flatness (the ability to focus the flat surface of the film uniformly onto the flat surface of the sensor.) Most true macro lenses are designed to have those traits; other ways of getting high magnification (such as extension tubes) may not, so that’s the main benefit of using a true macro lens for scanning.