Well that would have been useful in the five zillion times the hero ships have been taken over in the history of the franchise.
WORF: Where's that disable button?
THE END.
Tilly comes off better than Harriman or Esteban.
I found it much more interesting than most of the guesses out there and makes for a more personal story. And that's one of Star Trek's strengths. The Doomsday Machine is a superior episode to The Immunity Syndrome because of Decker 's presence.
The "somehow" is the child was mutated by his environment (dilithium, radiation, subspace). Not that unusual in Trek (Charlie Evans, Garth) and has vast powers, again not unusual in Trek (Gary Mitchell, Wes Crusher, Charlie Evans again).
Do we even know how long the Federation has been interacting with Bajoran, There is no official first contact with them. They seem to be a known quantity when we first meet them in "Ensign Ro".