Striders are not attempting to exit the water, even if they could.

Striders should exit the deadly(for them) water pool to prevent their dying

Striders prefer stay in water pool till death, even though they could easily exit this "trap"

1. built a pool, that striders can escape (For example 3x3 water filled place surrounded by blocks for striders to step on)
2. put strider inside this pool(spawn it there)
3. find out that they wouldn't like to escape from the pool