That too.
I was thinking of people who start the morning trip at ARN, go to GOT — or elsewhere west — and then come back to ARN so as to make an evening connection out of ARN that maybe allows for some time to use the Amex lounge in the late afternoon/or early evening too before it closes. But maybe the greater annoyance for Amex and lounge operator has been doing as I too have done: someone stopping in to eat first at the Amex pop-up, go meet up with others at the SAS lounge and then go back to the Amex pop-up. [FWIW, I did this mostly before the pop-up at ARN.] Whatever the motivation for the change, the change was done for some reason and is going to be an inconvenience or even surprise for some Amex customers.