With regards to the twisting you both seem to be correct, but you are talking apples and oranges.
The transmission line twist and the twist to make a cheap trimming capacitor are essentially different in that with the cheap trimming capacitor you are looking at the surface area of the one wire near the other wire, capacitance being caused by having a charged plate near a second plate (the twisting of the wires together create far more capacitive surface area than laying two wires next to each other - look at the surface areas exposed). The inductance created by the twisting is negligible in this case (but not always) as the wire ends are not connected to comnplete the loop.
With a transmission line over long distances, the twisting does add inductive reactance (it is a closed loop) The surface area between the two exposed wires is virtually unchanged (look at the distance between the wires).
