The French became involved in the American Revolution after Burgoyne's surrender at Saratoga. Interestingly,all this talk of "traitors" reminds me of the fact that at Bemis Heights and Saratoga another traitor, Benedict Arnold, proved himself to be the premire American field commander in the Revolution. However, France didn't enter the war for altruistic reasons. They felt that by being on the winning side against England they might be able to wrangle part of their lost colony (Quebec) back during the peace negotiations.
As for the missing flags, I'd rather have them missing then desecrated. Doesn't anyone remember the spray painted memorial in northern France? The one with the words written in French tellihng the British and American to come take their dead who were, by being buried there, polluting the country? I imagine the authorities removed the flags and pins to keep the place from being vandalized by those folks whose hatred out runs their sense of decency.
At least I hope so.