The way Fingon's sense changes with the notion isn't something Luke can read, but he's hoping it means giving it some thought, not rejecting it outright. Anyway, he has his own statement.

"Huh. Could you explain that a little more?" Luke smiles faintly. "My... experience with spirits moving from body to body hasn't been good."

A vast understatement. Luke's experiences with Cronal and the Reborn Emperor have marked him. Strengthened him, oh yes, brought him knowledge and power, but a shadow is on him now. Some of the knowing doesn't rest easy. Some of the power is too terrible to use.