Cardboard boxes

So it's coming up to Christmas and I buy many of my gifts online.
I often get my deliveries in boxes and have given one to my chinchillas after I took off any tape and stickers.

One of my chinchillas has taken a real interest in it and is chewing the box a lot!

Just wondering if it is okay to let him chew it so much or if I should take it out to stop him chewing it so much?