If the product is FOSS, then they're both legally and morally right to do so.

I actually support the enforcement of Trademark, though - its not about IP but product identity.

NVK is bringing an action under Trademark, if I understand him correctly. I don't expect him to be successful - IMHO the defendant is not impersonating his branding, and the similarities between the product names is only moderate. But a court will decide.

Either way, he's within his rights to initiate an action under Trademark, which in Common Law predates the modern state by centuries and is not really part of IP. 

 They look like twins. 

Djuri needs to turn up that creative dial and remix that shit better