For area type and type on a path, a path is a vector. You can do the same with
textPath as with other paths: recolor, change position, and more. The point array of a text path can also be manipulated: select, move, add, and delete.
While it is enough to select at least one point on a vector path to work with all the points, the text path has a problem. You have to select the whole path, otherwise scripting methods won’t work.
textPath has a property for getting an array of selected points:
textPath.selectedPathPoints, but you can’t use that either unless you select the whole path.
To summarize, the current API does not allow you to work with a partially selected TextFrame. You need to get the TextFrame by an index in the collection or select it and use the
app.selection array, otherwise
selection.length will return zero.