He appreciates her carefulness, but he expects that she doesn't need to be that careful.

For clarity's sake, he shows her his feelings in more depth:

If she had taken him up on his original offer, that would have been okay. Maybe not if she approached it like an Endarkened would, but she is not an Endarkened, so that's not really a concern. He meant it when he thought/said that it would be delightful. If she would rather avoid that whole conceptual framework, well and good, he has no particular attachment to it and is happy to figure something else out. But there are no dire harms lurking just around the corner; it has been ten thousand years, and he is okay.