The reason Morse code/the sat. signal aren't noticeably delayed is because they travel at the speed of light, so the distortion of the bubble is negligible compared to the subsonic rocket and the even slower chopper.
However, I think we have been assuming that the bubble around the island is uniform, smooth & constant. That may be incorrect. What if the bubble, except on that bearing of 325, shimmers back & forth like the aurora borealis/australis, creates little eddies, reverses polarity, or whatever metaphor strikes you as viable? Perhaps the Doctor gets killed three days hence, but his floating corpse gets caught in a time distortion eddy, which, as Daniel keeps mumbling, has something to do with our/The Losties' (mis-)perception of time. The fact that his corpse washes onto shore before it 'should' doesn't truly harm/change the timeline, for a bloated corpse can't create a Grandfather Paradox, for example.
We're gonna need such illogical hoops if they claim that the doctor was truly alive when Daniel beeped in. Ergo, I hope it's just a case of the Freighties lying!