Complex sentence: When Arnold was announced in his role he said that doing the closing ceremony was an honour and a once-in-a-lifetime opportunity, while Gavin stated that he was really excited and honoured to be involved.
Split into simpler sentences: When Arnold was announced in his role he said that doing the closing ceremony was an honour and a once-in-a-lifetime opportunity. While Gavin stated that he was really excited and honoured to be involved.