I actually think the St Johns stuff for someone wishing to join an airline as crew is also a waste of time.
Unless however there is a personal desire to do this training.
Again, coming to an Airline Assessment for the position of Cabin Crew and having St Johns training, does absolutely nothing to help your chances, it is not noted, nor are points awarded for this training being taken by a candidate.
The above may not be accurate for any other airline related role, however, for cabin crew... your wasting your time, the training for crew in relation to First Aid is designed for the inflight environment, and St Johns does not cover this.
Although it is handy to have if you are a regular person wishing to widen your knowledge.