What is significant about Scout's leading Boo Radley to a shadowed chair on the porch but not allowing it to seem as if she were leading him...

When Scout leads Boo Radley to a shadowed chair, she is
showing respect for the fact that he doesn't like to be in the light. This could mean a
variety of things. First, he doesn't want attention directed to him. Second, he is
literally bothered by light after living in the basement and not coming outside for
years. Third, a shadow is a sort of shade or ghost to a child. This is what Boo had
always been to the kids: a phantom. Now, to Scout he's
real.

A few moments later Scout
narrates:

I
led him to the front porch, where his uneasy steps halted. He was still holding my hand
and gave no sign of letting me go.

"Will you take me
home?"

He almost whispered it, in the voice of a child
afraid of the dark.

I put my foot on the top step and
stopped. I would lead him through our house, but I would never lead him
home.

Scout at this point
does go with Boo to his house, but he escorts her there. She realizes she cannot relate
completely to his circumstances and that people are all different. We must respect those
differences and she gave him the control from this point. This world he stepped into
with the rest of society for a few moments is one that he may have very well been afraid
of, and she respected that giving him the courtesy of a friend to walk home with and
nothing more.

There is much irony in these moments as Scout
moves from fear of that which is different to respect for the
difference.