why doesnt sidon swim?

silly question but why can't Sidon's avatar swim with me? when i got Sidon i really thought he would because i was used to Tulin chilling in the air with me when i was flying, and i got so sad when he just deactivated instead. i want to spend time with him!!! :((

is it something to do with the kind of abilities they have? though i'm pretty sure Sidon's water shield could help Link when he's swimming in the water.....