It make me think of Pacher (FDJ) who pulled the head group before the climb. What was the goal? Did he believe a fast approach would help Grégoire compared to the other guys? Why would it help him?
The actual result is that it enlarged the gap with his leader G. Martin who has crashed... And Grégoire cracked in the climb.
So I imagine, it was simply a case of "Damn, I am in a reduced head group with most favourites, I won't be able to do anything in the climb, so it is my last chance to act". Even if the action makes no sense, he showed he worked. That's my theory for this case 😀
It escapes me too.
On forums I read, there are always people defending them (there is even one guy asking for more!). The reasoning is particularly shallow, it always boils down to "there has to be stages for sprinters". Myself, I don't call this an argument, I call it a postulate.
This year, I haven't heard the argument that I used to hear: that these stages were 'transition' stages, connecting dots on the map to 'advance' on the global course of the tour without huge bus transfers. It was untrue 3 out of 4 times. Firstly, they often loop around, or go backwards, and do not participate to a logical geographical progression. Secondly, tours are not tours any more, they don't circle around a country or region, they are big spaghetti messes trying to build something out of a reduced list of towns who can pay the required bill, so the notion of progression is rather moot.
If we look at the general map, the stages of today and tomorrow can be seen as transition stages. But that's only because they insisted on going into Brittany for a single stage, and then in the Massif Central for a single stage too; while they spent the first 3 days in the North without progressing by an inch (despite 2 sprinters stages out of those first 3 stages: those were definitely not transition stages). Between Brittany and Massif Central, the landscape is pretty flat; however you could find a few hills and a few valley slopes if you wanted.
Keeping Brittany and Massif Central, they could have done only 1 stage in the North, then the rest of the stages would have been two days earlier (meaning those 2 flat stages would not have happened during week-end), and then added 1 or 2 hilly or medium-altitude mountain stages in the Massif Central before the rest day.
More radically, they could have put the rest day on Friday or Saturday and removed those 2 flat transition stages altogether, restarting a new sequence from the Massif Central, and eventually adding a sprinter stage at the end of this sequence after the Pyrenees, when sprinters teams are cooked and there can be a fight between breakaways and sprinters teams. It would have been OK with UCI rules (first rest day must be later than 5^th^ day) and better balanced than as it is now with 10 days in the first sequence and only 5 in the second!