I think that MIT is about as transparent as possible in the admissions process so I think that the letter is simply reminding alum of that fact to soften the blow if it were to happen that a student was rejected. It seems very un MIT like to send those letters to just those alum parents of rejected students.
Ooops, did not see this last page before writing post 42. Obviously I wouldn’t have written it had I seen Chris or Stu had replied.
NOT an unlikely letter!! 
congratulations!!! @fretfulmother
Thank you @gormar099
Turns out it was a likely letter after all, @fretfulmother!
@EastGrad you are too funny. “Remember we don’t do legacy, and this year is the most competitive ever. Oh, and FINE, you can come”