My DD was like this (and still is too some extent)
With her I do the bath, then feed her, her bottle, then she will crawl around on our bed for about 10mins, then I put her in her sleeping bag, take her to her room, put her in her cot, she will move round while I sing a lullaby, I say night night, sleep tight, don't let the bed bugs bite, I love you very much, kiss her, say night night again and then leave. She will move round some more just to get in a comfy position then go to sleep.
If he is arching to go into his crib just put him in.
he is usually rolling back and forth back and forth - sticking his legs and arms through the rails.....etc.,
I think that is a way of getting in a comfy position. Does he cry when he is doing this? If not, I would think just let him get on with it.
HTH