CBS/Paramount do not own the name, they own the trademark but that doesn't affect the usage of the name within a story.
Actually, yes, they do own the name. They have absolute control over any
fictional starship called USS
Enterprise.
This restriction does not apply to any real-world ship with that name (such as the aircraft carriers CV-6, CVN-65, and CVN-80)* - only those that exist solely in fiction. So for example,
The Orville could not have a ship called
Enterprise, because Planetary Union ships have USS as the registry prefix.
That's the key. The restriction only applies specifically to
USS, nothing more. So therefore B5 could theoretically have had an EAS
Enterprise,
Firefly could also have had an IAV
Enterprise, and SG-1 could have had a USAF
Enterprise.
Obviously though it's extremely unlikely that any of these shows
would have done this, even though legally they could. It's a gentleman's agreement that "Enterprise" should be solely reserved for Trek.
*I honestly don't know if the US Navy has any control over fictional use of its real ships. For example, CVN-65 appeared in ST IV (even though it was actually at sea at the time, and the USS
Ranger was used for filming). Did they have to get the Navy's permission before they could use it?