You are probably right. It's a bloody shame though. I'd love to take a pre-match pint to my seat to drink before the game started. it really is an antiquated and discrimnatory piece of legislation.
I stand to be corrected but in hospitality you can drink within sight of the pitch and it is only during the game that the curtains are drawn. If this is indeed the case I do not see why it cannot be extended to the stadium itself, to a reasonable time before kick-off, ie no entry to the stand...