To find someone temporarily in Mauritius to take care of her, he doesn't really trust anyone else. He had someone investigate this Joanne Harrison, and her background is clean. She indeed did a good job last time.
If it weren't for Joanne Harrison rushing to tell him in time, Enna Clark might have already followed the elevator down!
By then, he wouldn't have been able to save Enna Clark.
So, he brought her over.
If Joanne Harrison does well, he might consider giving her another job to take care of Enna Clark long-term. If she doesn't do well, it's enough that she takes care of Enna Clark these few days.
Of course, if she's tempted by the money and benefits outside and dares to have any ideas about Enna Clark, her end will be extremely miserable.
Before bringing Joanne Harrison over, he already had someone show her the mercenary video shot by Scott Harris, she should be very clear about the end he was talking about.
