This article is full of awful advice counter to the manufacturer’s procedures and any modicum of common sense.
The lift needs to be in a fail safe position at all times before working on the vehicle. This is auto lifts 101. Secondly the “double jacking” approach is extremely dangerous if the first rule is not followed. Support the vehicle with a secondary method is only advisable if you’re shifting the center of gravity significantly say with an engine or subframe removal once the lift is in a locked position.
If you can’t trust the safety locks on your lift you need better training on how to operate your lift or a new lift all together if you don’t like how the locks engage.