After his scan was completed, the old man returned to take Lucifer with him. This time, his entire perception was different though. He gazed at Lucifer more curiously and was able to understand why he said what he said.
He also understood why Joana was acting so smug. This boy, he was nothing like they had seen before. He was certainly somewhat special.
He took Lucifer with him to a separate room which was assigned to him, intentionally taking the longer route so he could talk to him more.
Lucifer told him everything that he had told the Star Alliance since that wasn't a secret anymore, regarding his history on earth and his appearance in space.
He conveniently omitted the thing about being arrested over accusations and being given this card. He didn't want the old man to be suspicious. Even though he was proven to be innocent, it was still better for him to keep such things a secret.