I dont suspect that glue will hold for long. He should have formed the wood and let it dry in place, then glued the pieces together and put back into the form.
Nice idea on the swing. 👍🏼👍🏼 But, as much as I love recycling/repurposing things, using plastic to make the casing for the cushion is not a great idea, because it will cause the person sitting on it to perspire and stick to the plastic cover. Repurposing clothing Is a great idea and I would have not only used the shreds to fill the cushion, but used either another piece of clothing to make a case or cover for the cushion. Or use an old pillowcase to cover the cushioning. 😉 Just my personal opinion.