Nice find!
Yes, that’s the way it should be. Companies that want to take responsibility for selling medical products can use 3D Slicer technology under the terms of the license with no charge. 3D Slicer itself, as made available on slicer.org is not such a product. Reading the pdf that Andras linked to is a good way to get a sense of the legal process of selling a medical product.
People interested in learning more about these topics may wish to study this course material: Yale course about medical software development