You didn't get it (to be clear for non-English native speakers : you didn't understand). This was IRONY. It was really harmless indeed after all the British insults the French had to endure for over 68 years, including "there were no brave French people 1940" (Peter Townsend in "Duel of Eagles"). It meant : "Were RAF Sqn Ldrs possibly as devoid of courage as the French?" (who had 30 % of their number killed in action in 5 weeks). If they had been 100 % of them would have been dead by October at the latest (this takes the lull 25 June-10 July into account). Were they?