It was the only logical option available for Alonso. Realistically he is never going to any of the top 3 teams . Thats RBR , Mercedes and Ferrari . Mclaren isn't available for him ,and STR has a pool of youngsters from their. RBR program . Then there's Haas , Alfa , Williams and Aston Martin . Of those 4 ,I think Aston Martin has the best hope of going forward if they can get it right . Alpine made up their mind about Ocon and Piastri . Piastri has a good future, Ocon ,well we've seen his best and he cannot beat Alonso . So that left Alonso with Aston Martin as the only logical choice