Yep, that caught my eye too. As far as I'm aware, the only Fremont that explored that region was John C Fremont, the American Lieutenant who explored much of the west and brought California into the Union. Considering that he passed through or near the canyon in the article four times during his expeditions, it's pretty likely that he's the source of the name.
BTW, I didn't even have to Google this...I went to John C Fremont Elementary School, and this guys history was required reading :-)
You silly gringo - everyone not blinded by your eurocentric propaganda knows the truth about Juan Carlos Frémont!