Yes, Sanguine-Choleric is a logical fit for ENTP. (Sanguine=ENP; Choleric=NT. Definitely saw Jenocyde's Choleric side in out meetup last night, but that's another story).
I never saw that whole trifix system used on the temperaments. That was for the elements -earth, air, fire, water, but then of course, those were associated with the temperaments too.
In that other thread, an NT may come up as Melancholic mixed with something else, but that doesn't mean that the Melancholic is NT. With some INTP's, they may come up Phlegmatic-Melancholic, but I believe that is the Phlegmatic (Interaction Style) tempering the Choleric into an appearance of a less aggressive Melancholic. The temperaments in the blend have tempering effects on each other, which is one reason I believe converting both the Keirsey temperaments and Interaction Styles into their Galen counterparts is good. You can see in each type what is being mixed.