No, it isn't. RGB is just a color model. You cannot convert between a color model and a color space any more than you can covert between float and Euros.
In order to convert between RGB and L*a*b you need a color space. That could be an ICC profile, sure, but it could also just be any well defined color space like sRGB, Display P3, or bt2020
It seems like you two agree on everything except what "device dependence" means...? GP acknowledged that there is no direct conversion between RGB and Lab, distinguished RGB from sRGB (implying the former is not a colour space), and indicated that a colour space like sRGB does solve the problem (since TFA is about using it to solve the problem).
No, it isn't. RGB is just a color model. You cannot convert between a color model and a color space any more than you can covert between float and Euros.
In order to convert between RGB and L*a*b you need a color space. That could be an ICC profile, sure, but it could also just be any well defined color space like sRGB, Display P3, or bt2020