I mean activated as in used for fighting not ward dodging.
He's not exactly using it in a fight. He uses it to get into one, not once he's already there. Eve does the same. Uses it to close, but not actually in the fight. It's the same criteria.
Whatever, Meddler already said Eve is currently the only one. She won't be at the end of preseason though.
Well, of course. Eve is the only one right now because she's the only character who decloaks when enemies get close. That's what makes camouflages different from stealths. By definition, she has the only one.
The point is, Rengar and some others have stealths which meet the criteria for what he said should be a camouflage. He said that long-duration stealths used for getting into fights should be reclassified as camouflages.
That's why the answer to your question of "So is there one whole category of stealth just for eve or am I missing something here?" is no. The category isn't just for Eve. It's for Eve, and the champions who use their stealths in the same way Eve does and will be adjusted to fit into the new camouflage group.