Sodomy would be worse because it’s not just a sin of lust but also an affront to the divine order of creation. In other words, neither an anus nor a mouth are meant to be sex organs.
One might visualize this as a vector in N-space, where the length of the vector (magnitude of the sin) is influenced by all the N dimensions. In this case, fornication is a vector only along one axis (1,0,0), and so is shorter than sodomy, which is a vector to the point (1,1,0), if we define three axes as ‘lust,’ ‘unnaturalness,’ and ‘interpersonal violence.’ Heterosexual rape would then be a (1,0,1)—equal in magnitude to sodomy—and homosexual rape a (1,1,1), worse than all of the above. You can add more dimensions if you want to look at other factors (for example, define a fourth dimension ‘unitive ends’, and masturbation becomes a (1,1,0,1) sin, since it involves lust, abuse of the sex organs, and personal isolation, but no interpersonal violence), though practically all we really need to know is that we should try to stay as close to the non-sinful origin point (0,0,0...0) as possible.
How about your hands? If you've ever touched yourself, what are you gonna do?
I don't see any real math there, just a made up way to confirm your bias.