Author of the guide doesn't even really need to get the platinum, but he looked at the requirements for the onerous trophies like the all iPod songs and the fact that you need to get all emblems and you can conclude you need to beat the game 8 times.
Like I mentioned elsewhere I think the best course is to do a first playthrough to get all the reg. trophies, then beat the game on Extreme, without trying to get BBE, just to stock up on ammo and stuff, THEN start yout BBE playthrough.
As I recall you basically need the Solar Gun or you're going to be super frustrated.