It was Deignan that sat up. She was 2nd in the hillclimb but knew she had no chance whatsoever against Annemiek in a H2H time trial, however Longo Borghini and Guarnier (her teammate) were not far behind. Lizzie would also probably lose to ELB if it came down to just TT prowess, but if they worked as a trio they could potentially chase Annemiek down. That worked fine, until they got towards the climb, as ELB stopped cooperating, knowing that she'd get worked over by the two Boels girls, both of whom could outsprint her, so she saved energy and attacked on the climb, dropping Megan but not Lizzie, who then outsprinted her into the Stade Velodrome at the end to preserve the status quo. Annemiek wasn't really under threat of being caught once Lizzie sat up and waited because she had enough of an advantage over Megan that by the time the trio had come together she had a big enough advantage to defend untroubled.
I actually think that, patterned after the skiing, they absolutely SHOULD allow drafting. It makes it much more tactical. However, they need it to either be a race with an MTT and a flat pursuit, or a decent length flat TT and a mountain pursuit, to have any reasonable hope of succeeding.