Scotland, who beat the Blitzboks with a last-minute try in London earlier this year to win the London Sevens, were up 5-0 at the break but were hit hard by a yellow card to Fraser Lyle that shifted the game in the favour of the South Africans.
It was first Senatla who spotted a gap and surged through to score before Rosko Specman won a kick and chase to take the Blitzboks into double figures.
Senatla closed off the game with a late try to take his tournament tally to four in two games after scoring twice in the opening game against Uganda.
Earlier in the day the Springbok Sevens team kicked off their 2016/17 HSBC World Rugby Sevens Series season in style, scoring eight tries as they swept Uganda aside 46-0.
