The parents arms look like they were trying to prop the kid up and then get out of the photo quickly. It doesn't work. Even if you sat the baby on the floor criss crossing his legs , it would be better. (it takes him longer to to get up, should he be so inclined, when you do that). If I have a baby that needs wrangling by the parents, I have one of them on their knees and I draw an imaginary wall on the floor telling them "you can lean in if you need to touch the baby, fix hair, wipe the drool, take outs out of mouth etc. but as long as you don't cross THIS IMAGINARY WALL, you won't be in the picture... Ask them to NOT talk to the baby, only to wrangle him. The baby will feel comforted having a parent nearby also. The other parent can be behind you, but avoid having them trying to get the baby to smile if possible. That can be your Plan B. YOU need to try first, so the baby is looking at the camera.
Give the wranger parent a visual by drawing the imaginary wall with your hands so they know exactly where the baby wrangling parent can and can't be. They can't sit on their butts and still lean in comfortably, but on their knees they can be close enough and far enough to wrangle/protect the baby. You need to give enough space to crop them out if they mess up afterwards. Remember, being on their knees gives them a lot more "reach", it really does work well.