Its not that the 13 year old killed a buck that makes him mad, its the fact that he killed a young buck that had good potential. There are plenty of bucks running around and if that kid would have waited alittle longer then he probably would have been able to take a more mature animal. Theres no point in killing an immature deer when there are plenty of mature ones around.
Where I hunt , management is very important. Killing an immature buck with potential is a huge no-no, and sometimes, depending on the lease agreement, could cost somebody some pretty substantial dollars. You wait and take a mature animal, or if you take a young buck, you look for an animal to cull. Where I hunt, any 2 1/2 year old or older with six points or less, and no brow times, is considered a cull.
That said, a mature buck where I hunt is usually a 4 1/2 to 5 1/2 year old.
Climate can be downright hostile, and food supplies can get very low. The older bucks sometimes just don't bounce back after the rut, and die off in January and Febuary. There are some older bucks there, but they are few and far between.