So does it only work for attachments, or can it work for objects one is sitting on? If the former, I already knew this--attachments do not affect an avatar's physicality, and because an attachment is necessarily attached to a physical object, it is effectively physical by attachment, so whether or not it's been set to physical doesn't matter--it becomes physical. If it's the latter, on the other hand, that would be something interesting.
Nope it can't work for something you are sitting on. The comment was made regarding a question posted about flying higher with a flight control scipt. But still at some point I guess it should be mentioned in a note in the wiki that it is not necessary in an attachment.