This might help explain morph surface tubing a little more...
Sorry, I don't understand what it is you want to extrude.
You can either create a morph surface and extrude (tube) that with the pet pallet option.
Or you can create a complex profile that you can use with the wall, beam or column tools.
Either way the profile you create will be a cross section at right angles (perpendicular) to the path you extrude.
The Archicad YouTube channel has many videos.
Just try searching there for what you want ....
In amongst all of the morph videos, you will see one about 'tubing' with a morph.