Not exactly, he's letting his weight fall forward briefly to hook Kanitah's legs, it's easier to hook someone's legs from the inside when you're already tight to their sides, to hook your legs out from below they'd have to make their legs bend inwards past the natural width of their waist if you get what I mean.
It does require him to relinquish some of the grip he had around Kanitah's body with his knees though, but in theory the grip is maintained by the hook legs instead. (I think maintaining contact is important in grappling with two super humans, because they have to contest eachother with strength rather than using body weight which most fighters would use, being down on ones back isn't really that much of a disadvantage to an opponent that can easily throw Fury's weight around like it's a bag of flour)
It's kind of a complicated situation. Actually, I'm going to have Fury attempt a choke rather than trying to control the arm, I think it suits his character better, give me a moment to edit.