I agree, the MS CM is incorrect. I've been an AP holder for 10+ years and the day you exchange the voucher for the real AP it has that date printed on the back of the ticket. That date is your activation day and a year from that is your expire date. If the PP activate on one day but does not use it until the next day, they will lose a day. But it's all relative since most of us only use our APs a couple of times a year for our multiple trips. I agree that you do need to crunch your numbers to see if a new AP is a better choice than renewing. We always renew because we go the same time each year and our AP always runs out mid-trip.
Just checked: even though my pass isn't due to be renewed until October, the website did give me the option to renew. Though I'm a
DVC AP holder, you do have log into the AP website to renew. Once you enter your ID info, it knows you are holding a DVC AP and will offer you the DVC discounted price of $304 to renew your AP. So that pretty much throws the 30 days out the window.