I can see his point,
If he offered to help and the police turned him down- more fools them.
Now he is on the case and yes, he can comment. He's doing this free.
They did 3-4 miles of river yesterday and he says the rest will take another 2-3 days ( the river is 12 miles to the sea.)
The reason he is puzzled is simply because in all his years as a diver he'd have expected to find a body now.
The reason he hasn't is (IMO) that there isn't one.
There are no signs of slipping.
Her dog didn't stay with her (which is what dogs usually do)
she had no reason presumably to go so close to the river bank, as an experienced walker who's done that walk thousands of times.
Her dog was dry. There was no ball to retrieve.
No one heard any shouting or screaming.
Why would she put her phone neatly on a bench if she was walking away from it?
If she fell in by the bench- let's just say she did leave her phone on the bench- then she'd have been found in the water near the bench.