OK don't laugh. I never thought about which hand I hold the torch
in. I taught my self how to solder so I was not guided by a teacher.
I had to go into my shop and do some soldering to determine which
hand I held the torch in when soldering.
It seems I hold the torch in either hand depending on the solder
job. Its the left hand if I need control of some precision part of
the process. That allows me to use my predominant right hand to work
a solder pick, wire solder, ETC. If everything is set up and I don't
need to control anything but the torch I hold it in my right hand.
Seem to me what ever works for you is OK.