Trademark is not a globally reserved word. If you are not doing commerce in relevant area that there can be confusion (or you don't imitate the logo), you are free to use it. This is basic free speech.
Besides Orca is a registered trademark used by multiple class 9 businesses, now what.
Okay I give you that. Of course it requires market and commerce, or it would be at odds with free speech. But I see how in this scenario this Orca may want to sell stuff later (like some OSS does these days) so that would be a problem for them.
But... how that makes it OK to go to collide with a venerable OSS project? Because Gnome won't sue? The scope of words that are not registered or considered these strong trademarks is still nearly infinite!
Besides Orca is a registered trademark used by multiple class 9 businesses, now what.