Being gentle is definitely a key here. I do shine GG this way every few days and haven't had an issue yet. If a major disaster happens, I will report on it and will possibly switch to another method. But the fact that it takes about five minutes to get GG nice and shiny is very appealing.
It can be done in 5 minutes both way.
Look at bishopheels video when he made tutorial on ultrasonic bath.
After the ultrasonic bath he made a polish to the GGTS using the alternative method:
Holding the parts in hand and press them a little on the polish ped.
It take the same time,and give the same result,you even may like it better.
When we give advice better to be aware not all feel and handle power tools the same.
No all understand or aware that some times things go wrong,and not everyone hand tools
or the way of handling there tools are of the Same quality/capability.
If you feel ok with this method,with your tools then there is nothing wrong with it,but I bet that with all
good intention you wouldn't like one report back on some unfortunate happening.
So sometimes one give or add his advice and the some
of all or part of it is what the other choose to follow.
I do believe it's better this way.