The sounds inside a synth/rompler, are designed/produced by the developer of this product(including also their sounddesign team etc) so in short - the sounds are designed by them - if you record them, it's the sample like a copy, so illegal!
If you design on a synth or rompler OWN sounds, which are defintiv programmed by you, than you can sell them as soundset or sample-bank.
But sampling factory sounds(which are saved with copyright) is LOGICAL illegal....... Also if in the depths of the www surely many selling sampled factories, it's 100% illegal.
See this comparision, imagine, you would design a soundset for the access virus, so for example, and someone would take this, record it as sample-set and would sell it - this would be same illegal, but this is exactly the same as sampling a factory
