Of course a seal is smart enough to get away from polar bears, otherwise they’d not be around.
The point though, as it’s been staring you right in the face from the outset, is that their limbs aren’t “functional” beyond hobbling around on land. They’re not in some point along a ga-jillions year timeline in becoming flippers from legs or legs from flippers.
God made them the way they are. Period.
The point is that seals intermediate limb is not a fully terrestrial or fully aquatic limb, and yet they are perfectly adapted to their lifestyle as not fully terrestrial or fully aquatic.
So the argument that a multi purpose limb would be useless for either is bunk, as thousands of seals can tell you.
Nobody said anything about transitional limbs being useless
Uh, yeah, metmom did in #557: "what good would a partially formed limb that is transitioning from leg to flipper be?: