Quoting AsstChiefMark (Reply 1): A Jeep isn't the safest vehicle to use at high speeds. One little twitch to the steering wheel and over she'll go.
I don't think 60-70 knots is "high speed". And that's assuming he kept the speed a bit high. It's also probably perfect for the occupants safety. It gives someone the ability to stand upright, and have something to hold onto at a good height for support.