If he entered the main straight around 6 tenths behind, he can gain enough through drs and slipstream to get into a proper divebomb range. On the other hand what actually happened was after the lockup he was slightly further behind and entered the main straight on lap 70 seven tenths behind and too far back to get in place for divebomb.

Edit - I also get why he did it but it was a mistake nonetheless. Shows that as good as he has been, he is not perfect. We have a cracker of a championship battle on our hands