I have never seen an instructor touch the resistance on anyone's bike! As a former aerobics instructor, it seems like a highly contraindicated move. And embarrassing for the spinner.
I had a lot of trouble standing when I first started spinning. I had only been riding a short time (the fall) when i started going to class when it got too cold out. I just could not get myself up! I also had a lot of trouble standing on the road and although I can now, I rarely do. It just hurts my knees too much. I do stand in class now, but I never do jumps. In fact, a lot of the time I do seated climbs, even when everyone else is standing.
It's your ride....