It wasn't Jon who sold the shares it was his daughter who is the beneficiary of a Trust in her name and which is part of the family holdings company.
It was the Huntsman Family Holdings LLC. The Form 4 footnotes explain:
"At the request of the Trustee of the Kathleen Ann Huntsman Trust, Huntsman Family Holdings Company LLC sold the shares covered by this report for the benefit of, and distributed the proceeds of such sale to, the Kathleen Ann Huntsman Trust. Kathleen Huntsman, an adult child of Jon M. Huntsman, is the beneficiary of the Kathleen Ann Huntsman Trust. Neither Jon M. Huntsman nor Peter R. Huntsman had any pecuniary interest in the shares sold in the transactions reported in this Form 4."