Is Schweser wrong? wrong, mistake, refers, middle

Wendy01

B5, p158, first bullet point in middle of page: "The slope of the line remains constant with CPPI"

Here the "line" refers to CPPI's Payoff diagram, which is Figure 12 on p162 . It's a convex diagram, so the slope changes at every point.

I think Schweser simply made a mistake, which has not yet been reflected on their Erreta page. Thoughts?