question

The object's location is not shifting. The object's direct spatial location is {-1.0, -1.45, 0.0}. After resizing, that is still the object's direction spatial location.

The confusion comes as to what the object's "direct spatial location" means. That is the location of the upper left corner of the object before any rotations have been applied.

When you rotation an object, that position is still its direct spatial location, which you can see by selecting "Direct Spatials" as the reference point for the object's location.

As Ralf explained, this object rotates around its center position rather than its upper left corner location position. This makes it so that when you change the size, you change the center of rotation, which makes it so that actual direct spatial location of the object doesn't align with the upper left corner of the object.

In order to keep the object's upper left corner stable as you resize it, you also need to set its location relative to the corner you want to keep stable. You can do this by getting its location relative to the upper left corner, setting the size, and then setting its location back to its original position, relative to the upper left corner:

Object obj = current.up;
Vec3 referencePosition = Vec3(0, 0, 0);
Vec3 prevLoc = obj.getLocation(referencePosition);
obj.setSize(obj.size.x + 2, 6, 1);
obj.setLocation(prevLoc, referencePosition);

Another option could be to change the object so that its rotation is relative to its upper-left corner instead of its center by changing its centroid attribute to 0: