As long as I wasn't leaving my machine, I would let anyone use any of my machines - some that have cost $1,000's. I feel if I am confident that my machine will easily sew what is being sewed, that it has the proper needle and is threaded by me; there should be no problem. A quick lesson on the importance of letting the machine feed the fabric and not pulling it through should be all that is needed for most new sewers. You can usually id those that should not even be allowed to use a hand needle, let alone a machine - LOL. No problem, I like to encourage sewing - I have let me daughter, when she was 10 years old, use any of my machines after a few lessons. I think the most important thing is what you are comfortable with - not what someone else would do, as you are the one that would have to live with any of the consequences.