Young or old, tortoises pretty much do what they want to do. If they are at a good temperature, all tucked in & feel safe from attack, seems like they will feel comfortable enough to sleep in that position.
Of course Daisy is not hibernating this year and her enclosure needs to be bigger but I hope to move in the new year to a bigger flat. When I'm I take Daisy out of her enclosure for a few minutes to allow her to stretch her legs but in the summer I let Jacky (who is hibernating in a pet carrier) and Daisy spend time in the garden.