Disabled Multitask Gestures / Keynote

I have disabled multitask gestures on my ipad pro, but the 4-5 finger pinch gesture is still enabled when I'm in a Keynote presentation. I am running the ipad as an interactive kiosk so I do not want patrons to be able to exit the presentation. When the gesture is applied, the presentation ends and reverts back to Keynote's slide editor screen.
Thoughts? (Note: there are various buttons on multiple slides, so using the Guided Access function doesn't really help for this application)