My point was that if he's a kid - regardless of his chronological age - they surely wouldn't have him on the bridge
If the point was to have a Klingon in Starfleet, then certain shortcomings could surely be overlooked. It's not as if Worf actually did any damage by being a brainless hothead anyway - Picard turned down all of his input as a matter of routine, as if he had been instructed by Starfleet to treat the politically convenient but immature officer as pure window dressing.
Plus, the Starfleet Academy course is three/four years by itself!
Not for the Ocampa, I guess...
Plus, at fifteen, Worf might already have had plenty of Klingon military training that would allow him to skip most of the Academy.
In this putative alternate treatise of the character, that is. The way Worf was actually and eventually described in TNG precludes the possibility of him already being a full Klingon warrior when he goes to the Dark Side and joins the Federation.