Because if they were all pistols.....TC would give up any sales to persons under 21 years old.....and....in states that have more restrictive laws regarding handgun purchase (MO for one).....people would be forced to jump through the handgun purchase hoops to buy an Encore or Contender rifle....can you imagine how many sales of Encore muzzleloaders (legally classified as a firearm by the way) would be lost if they required the same purchase critera as a handgun???
The part of the letter that I find most disturbing is the part that states that a person is guilty of a felony if they possess an encore or contender rifle that has been illegally configured.....even if the person possessing it doesn't know it is illegal! Since the frames of both rifle and handgun are identicle and bear no marking to distinguish one from another, makes you think twice about buying a used contender or encore if you don't know for positive that it started out life as a handgun!!!