BMI is a good indicator for the population as a whole. But like all such indicators it breaks down for specific groups: rugby players are just such a group as they tend to have a higher muscle bulk than most.
Don't forget that total weight is also a big factor in the RAF, certainly if you want to fly on a bang seat. If my memory serves me 93kg nude weight is the upper limit for flying on the current range of MB seats if you want the zero/zero performance. Lots of very fit athletes will find staying below 93 kgs could be a struggle. Lots of couch potatoes will struggle too! I occaisionaly hit 93, but I'm not saying whether I'm the athletic or couch type.
Keep up the aerobics and leave out the weight training for a while.