Ah, I see. Thnx for the explanation.
Shape is not transform is the short answer ;] But indeed, it is not logical for the user to have the shape parameters 'change' if we do an offset path. Might be how Ai works internally, but for us users it makes little sense.
It did make me acknowledge the difference between shape and transform. That helps :)
I have upvoted the request in your link.

There is an actual request to make Offset Path respect the original position and the direction of a path:
http://illustrator.uservoice.com/forums/333657/suggestions/48230837
Please upvote it if you want this as an option!

Renny, there is an actual explanation.
Let me show.

1. Grab the Rectangle tool

2. Draw a narrow horizontal rectangle, starting from top left angle

3. Open Stroke panel and assign endpoint arrowhead
As you can see, the last (and the first point) of the rectangle is the point where you release the cursor

4. Now make a copy of this rectangle and rotate it 90°
Check both, comparing their parameters in Transform panel — to see both the Width/Height AND Rectangle Width/Height — since these are two different things. The path’s width and height are just X and Y lengths. The shape’s width and height depend on the rotation of the path relative to its starting point. That’s why we can select both copies of you rectangle and change their 'rectangle widths' at the same time — that’s why we have live shapes in the first place! You can rotate a rectangle to an arbitrary angle, and Ai will still allow you to change the rectangle’s dimensions... while the path’s width and height would become recalculated according to the rotation value.

5. Now select both and apply Object > Path > Offset Path.
Do you notice anything strange?
Even thought the starting points differed for both paths/shapes, the new ones Ai assigns are the leftmost-and-bottommost ones — despite the original position of starting points.
But since it makes an offset path of a rectangle into a rectangle (makes sense), it leads to 'swapping' you observe.

In other words — if you lay down, you height won’t change, right? :)

It happened when I 'offset path' of an normal drawn rectangle. The original does show correct info on Control bar, but the offset one shows the swapped info. Buggy ;]