I would take pictures and email them to the organizer/chair of the group. I agree that completed quilts reflect on the entire group, so they should be made aware of sub standard work. The quilting designs may not be pretty (given the volunteer long armers), however they should be done well enough where you shouldn't worry about the quilting coming out.
I also agree with Feline Fanatic. If the bobbin thread is just laying on the back, it shouldn't take much time at all to remove the quilting. Ask me how I know ;-)