It's the samples in their raw form they are talking about... in fact that is not only 8DIO that make this claim, other sample manufacturers do this as well when they sell sample packs... they restrict you from resampling the waveforms in their raw form, or even play them "stand alone" in a composition... the hint here is: Change the sample in some way, so that it does not retain it's original raw form, and you're good to go... you have (so to speak) to make your own imprint on the sounds.
So if you use their samples in the PX engine, to create something that does not sound EXACTLY like the raw material, you're good... and if you did not do that when creating a PX program, then what would be the reason for that? that is what you want to be able to do with a sample synthesizer anyway; mangle the shit out of the raw building blocks. It's like if you were allowed to create designs using LEGO, just not creating exact copies of the LEGO bricks themselves.
They do not want to restrict you making music... they just want to restrict you from selling their samples so they can be used as building blocks in other gear as well. In theory you could even create your own programs using their samples, and then sample those programs and sell those as a sample pack because these samples are NOT their samples in their original form... they are altered by the synthesis engine completely... they are only BASED on the raw building blocks.