Lex did not immediately head to the turtle. This issue was particularly sensitive. He did not want the turtle to leave the safety of the Inn, especially with Zuri acting so suspiciously. Her offering Lex some genuine aid did not alleviate his suspicions, but just made him even more confused about the nature of what she was planning.
There was, of course, the possibility that there was no plot and she was sincere.
But it was hard to believe, and he didn't want to risk something so major on a mere possibility.
The solution was simple. All he needed to do was give up on his plan. He could use some other tree to build the treehouse, or decide to build a castle instead. Things did not need to be so complicated.
Yet Lex could resign himself to giving up just because the situation became complicated or troublesome. What king of supremacy did he have if he dared not display it when there was trouble?