These tools provide at compile time the required functionality to process, manipulate and transform a CrossMobile project, to be able to run under different platforms. It also provides the tools to create native bindings and external plugins.
These tools are not required by runtime environment and are completely independent from runtime. They don't have any relation with the original project code or the produced project code. Thus these tools do not govern, deal, or have any implication with the final project, being open source or commercial.
For more information have a look at the base CrossMobile repository or at the official CrossMobile site.