This is just a mere illusion. In reality, the peak wavelength is actually between green and blue, that is slightly cyanish/turquoise. The reason this happens is because the atmosphere of Uranus contains methane, which has an absorption wavelength between yellow to red leading to blue/green reflected wavelength. In the albedo of 30% of the sunlight reflected by Uranus, blue green light is absorbed the most.
This wavelength is however scattered in our atmosphere, via atmosphere refraction, specifically Rayleigh scattering which leads to telluric absorption which leads to a few wavelengths being scattered more like blue wavelengths, which is precisely observed in the ground-based telescope images. In space-based telescopes where there is nill telluric scattering, the actual color is perceived.
Even though the green color is more sensitive to our light cones, green light is already absorbed by our atmosphere, before reaching our eye.
This is quite similar to how the Sun's peak wavelength is green, but we perceive it as yellow, except the atmospheric refraction is different in this case.
It's not leaned towards pure green or pure blue. The Rayleigh scattering absorbs only few nms, like around 30-40 nm.
This is a mere mirage by the atmospheric scattering of the Earth, aerosols like to absorb more green than blue due to their electrons and quantum mechanics even though Uranus is lying between green and blue.