Lex was extremely conscious of what he told the mysterious and totally-not-suspicious magic orb about the universe. He didn't actually know anything about Regix, except that he was super old, suffering from a curse, and could hack systems. The dismissive way in which he treated the concept of Dao Kings and influencing the universe made Lex think that he had interacted with them before, and that he was not a nobody.
In that case, whoever cursed him was also probably a super big deal. Lex was somewhat conflicted between never wanting to see him again, and questioning him for everything he was worth. Unlike everyone else he'd ever met who knew about systems, Regex did not take them seriously at all. His social awkwardness aside, the very fact that he caused Lex's system to show prompts to share data was just insane.
