What's this gate doing here

Mommy took the gate and put it in the door that goes outside and leaves the door open for me and the kitties. I really like to stand at the gate and talk to Jack when he's outside. Sometimes Chloe sits with me too. She doesn't even growl at me when I pet her like this.
Sometimes the floor is cold and I don't like that but I have to get back to Mommy so I crawl like this. Mom thinks it's funny