I'm not sure why people think she isn't. She's been around way too long this arc and even received a vs title card with Kid and Law.
I think its pretty obvious Oda wants to at least paint Luffy and Kid as equals by the end of the arc (assuming Law doesn't contribute to the entire Yonko fight)
How will Kid be equal to Luffy?
The guy is behind Luffy who has all the advanced hakis.
And who beat Doflamingo, Cracker and Katakuri. The guy splits the sky with Kaido. And is about to beat the strongest creature in the world in 1 vs 1 (Kaido is weakened but still).
But Kid, we're not even sure he's beating Big Mom with Law.
I repeat with Law. He's not all alone.
Why you want to force him to be equal with Luffy when from the start of the rooftop fight Oda has shown us that Luffy is clearly stronger than him with a long lead. Do not take your desires for facts that this is not the case.
I'm not condemning Kid again but you have to be honest and objective. On what Oda shows us.