As suggested (privately) by Alessio, I just added this sentence:
- You may not use Word Marks and Logos for commercial use unless explicitly granted by Nethesis.
For example, a consulting company can describe its business as “123 Web Services, offering WordPress consulting for small businesses,” but cannot call its business “The NethServer Consulting Company.” Similarly, a business related to NethServer themes can describe itself as “XYZ Themes, the world’s best NethServer themes,” but cannot call itself “The NethServer Theme Portal.”
Please note that it is not the goal of this policy to limit commercial activity around WordPress. We encourage NethServer-based businesses, and hundreds of them are thriving while in compliance with this policy.
This is from http://wordpressfoundation.org/trademark-policy/.
Is it better?
You absolutely can...well, you should! 
See this section:
You may make promotional goods for free giveaway at open source conferences and events using only the designs found on our site.