What the hell are "other payment solutions"? If you run out of cash at the Games, are Visa going to sign you up to some instant credit thing? Or do they have a hotline to your bank details and a card-printing machine? Something here strikes me as exploiting a captive audience.
The message is clear. If you're attending a London 2012 event and don't have a Visa card, make sure you're stuffed with cash before you arrive. Or just bring a packed lunch and empty water bottle, and avoid the urge to buy a souvenir bug-eyed mascot, and you should be able to enjoy the Games without prostituting your finances.