The client feared that visitors would try to scroll horizontally on the sticky section and that nothing would happen - so I converted horizontal scroll into vertical scroll using mousewheel.js.
Here it is working on a clone of Vincents Demo.
Scroll horizontally using your trackpad or by holding shift + mousewheel and you’ll see how it works.
And here’s the cloneable Webflow site.
Check out the JSFfiddle for more detail.