Wexler Tab 7t

I am very interested in one question.

The company “Wexler” says the source code of the software is not laid out in relation to their non-disclosure agreement with “Nvidia”. Is this true, and why it’s done, because “Google” laid out source “Nexus 7”, as well as on “Linux for Tegra” laid out the source for the kernel? This tablet, because of its low price, has become very interesting for developers.
In advance I thank.
P.S. Sorry for my bad English