NTSB investigator just said the he actually started to takeoff earlier in the day, before the crash, climbed to about 5' above the runway, then stated he wanted to cancel takeoff and return to his hangar. He later tried again...
I just listened to the tape... "earlier in the day" was at 8:46 AM (also on the same 15:30 recording, 16:46 in), he is cleared to depart 10R, right downwind, proceed on course. He cancels his takeoff and says "Uh 1LC is going to land here and stop; we have a problem to fix." Tower asks if he needs assistance, he says "Negative, I'm going to taxi back and see if I can figure it out." He's told to contact Ground at 8:47. Ground isn't covered by LiveATC.
At 8:54:30, LC is back on frequency, saying he'd like to stay in the pattern. (remember, his earlier clearance was to "proceed on course", so presumably he's staying in the pattern to ensure he "fixed" whatever he thought was wrong the first time). He's cleared for takeoff 10R at 8:54:37, "make right traffic". At 8:54:50, Tower gives current altimeter, says that Information Romeo is current, and advises caution due to birds in the vicinity of the aircraft. At 8:55:32, there's a brief transmission, unidentifiable, then the tower clears somebody else to depart. Before the departing traffic replies, LC is back on with a hurried and distressed "321LC, I'd like to turn back in, and uh... land... coming back in..." (8:25:45 completes that exchange, though the mike stays open for two more seconds and you hear "uh, 32!") followed immediately by background voices in the tower on the open mike crying "pull up!" and "oh, sh**". Takeoff clearance is canceled to the other aircraft to a chorus of "oh my god oh my god oh my god" from a lady in the tower.
NTSB says he was thrown clear of the wreckage but not clear of the post-crash fire.