No, more room for luggage, thus less luggage on seats giving more seat availability.
I've travelled on the 0900 GLC-PNZ a few times. On all occasions, staff have been really good on approach to Edinburgh clearing "bag" seats. They always are polite to the customer, explain that the seat is needed beyond Edinburgh and that, if it's alright with them, they'll put the luggage on the nearest luggage rack. They then proceed to move the luggage for the customer. Never once has a customer refused this offer (well, when I've been on the train anyway) and if they did they'd probably be forced to do so anyway. Certainly if someone had a bag in my (reserved) seat, I'd ensure that it was moved.