You say:
You seem to think that the fact that it is not juxtaposed together with Arayos is proof that the Rambam held this is some kind of chok.
But I said:
I think I saw the Rambam say explicitly that the reason for the Issur is that the early Ovdei Avodas Kochavim used to mix the clothing purposely.
What I was referring to is: http://hebrewbooks.org/pdfpager.aspx?req=9463&st=&pgnum=91
What you ask about Bechukoseihem is actually the Torah’s preface to Arayos all the time — not to follow the actions we’ve witnessed in Mitzraim and Kenaan.
Favor: Most often, I view the CR with my phone and can therefore not read the Hebrew characters. When addressing me, please try to transliterate.