Hi JJDa,
While there is probably nothing in the 'rules' of the At-home GMAT that require that you sit in a chair during the Exam, if you chose to take your Official GMAT while standing the entire time, then the Test Moderator would almost certainly note that (as standing is NOT the norm) - and this might lead to a more detailed and thorough review of your Exam (again, because an abnormal situation might mean that you're attempting to cheat). By extension, I would not be surprised if there was a delay in receiving your Scores (and potentially a 'voiding' of your results - especially if there are any other abnormalities during your Exam). This is all meant to say that taking the Exam in a normal, seated position is likely the better choice.
GMAT assassins aren't born, they're made,
Rich
Contact Rich at: [email protected]