Apparently a blending of step with set foot, perhaps by confusion.
Step-foot Sentence Examples
"There's a secret portal in the underworld, similar to the one here in Hell that allows Immortals to come in and out. It's how I could visit you when you were in Sasha's zoo," Gabe explained. "I couldn't take Katie through the shadow world place, because Death and Darkyn had assassins waiting for me to step foot in there. The secret portal is in Death's palace."
Because of her harrowing experience on an out-of-control roller coaster, Julia refuses to step foot in an amusement park.
Before you even step foot into a rental shop, you should know a few things.
Cook has refused to step foot on a Yuk-Yuks stage again.
At that time, he promised not to step foot on stage until his youngest girl graduates from high school in 2015.