55 knots on final for our fleet of J170's. 50 knots for a short fielder. With a stall speed of <=45 knots, it makes perfect sense.
Anything higher than that is at your peril and one of the reasons why so many Jabs have had runway excursions; schools are often teaching them speeds that are far too high and when things go pear-shaped, it all happens very quickly.
At a guess his speed was probably about right as he held back-stick for quite a while and if he had been too fast, it would have started climbing.