on the malware it doesn't. 

But a TM does protect merch that is sold using the brand trademark, that can be used  to raise funds that back to supporting the project. That's where the business value comes in and also bootstrapping to keep it going where it otherwise would have to depend on grants/donations 

 But why should the owners of the trademark tell you what you can print on your shirt?

Trademark, patents, copyright etc all violate the property in real scarce assets, just in order to create scarcity for a non-scarce information. 

It's such a destructive idea.