How would a (broken?) spoke go into the chain and cause a crash? It will not lock the wheel or anything else, except at the worst, you could not pedal. Back in the day, I broke many a spoke, never caused a crash at all. to the OP, for now you should leave it on as protection against the chain dropping into the spokes due to an over-shift. This could be caused by two things primarily. Over time a rear deraillier may come out of adjustment as the high limit screw backs out, or much more likely, a minor spill or bike falling onto the drive side may slightly bend the hanger causing a maladjustment. Until sucj time as you are able to assess and adjust the deraillier, leave it alone.