I’ve done a few rounds of interviewing over the years.
Delta T it’s not an exact science and rarely is a candidate knocked back for one thing only.
I’d be very surprised if the company who wanted to see you lead the group exercise was very happy with all other components of your application/ interview.
It is more likely ( in my opinion) that the interview panel had reservations about something based on either the sim exercise or your aptitude testing or your panel interview, they were probably 50/50 on you and were open to taking you if they saw something to counter their reservations in the group exercise.
I obviously have no idea if that’s what happened but my point is that it would have been a lot more complex than “ DeltaT didn’t lead the group therefore he/she is not suitable”.
I hope that is useful in some way.