The Forza 3 disc that was used for piracy was a review copy, it was an earlier build, yet somewhat final, of the game, it had the same features but had bugs the retail didn't had. Therefore PD could have removed or blocked feature on a review copy, but we haven't heard of reviewer playing the game, there is no review copy out there. Considering copies were stolen within a week after the "gold" announcement, those are retail versions, not reviews nor previews.
Also, Sony delayed GT5 for sdk 3.5 to prevent piracy, another achilles' heel for piracy on the PS3 is the PS Network, DLCs and updates. The game aren't run from the actual game launcher, but a custom software that doesn't check for copy protection, that software, in almost every game, can't run code that isn't on the Bluray disc. Sony and PD must have taken the decision to lock certain features out of the Bluray, like the museum, maybe tone down the damage, etc., until you do a very small day-1 update through the internet, you can still play it if you can't update the game, but you will be missing out. That's one possibility. It's what Forza 3 did with day-1 DLCs, since most people don't have a JTag xbox360, they are missing out.
http://www.ps3news.com/subdomain.php?pagename=ps3-jailbreak¤tpage=2&s=7
this is to illustrate my argument, not promote piracy.