What a load of nonsense. It is even easier to install pirated versions of paid apps on the PB. It is only with the OS 2.1 beta that there is even any sort of protection against it AFAIK. Apps downloaded to a PB with OS version below the 2.1 beta can be extracted as BAR files and posted online. Those extracted BAR files can then easily be side loaded onto any PB also below beta 2.1. One big site for downloading the pirated BAR files went down recently, but I am fairly sure there are still dozens of others. It's not that hard to find pirated apps online (I have never downloaded any of them, but I was just able to find within seconds a ZIP claiming to contain over 100 cracked games in one download).
Don't try to pretend piracy is not a problem on PB. It is a huge problem, which is why sideloading was, I believe, changed a bit in the 2.1 beta.
Please note that I do not condone piracy in any way. I am just strongly against misinformation as well.