It's not about simply getting dropped or being strong. It' s about his form being good enough in the third week to potentially reel in the overall there, while being bad enough to lose too much time in the first week, in case opposition tries to get rid of him. In this scenario, we're not talking about "being good" in the third week, but about him being dominant enough to win. As opposed to how his form would be in the first week, which would be anything but, in order to lose so much time, that with his form of the third week, he would not be able to make up for it. The premise proposes a steep curve of form, where rivals definitively blow him out of the GC race when his form is bad, to prevent him making up for it 2 weeks later assuming he would dominate them. While it's possible that dropping him 20s on stage 4 is enough to prevent him from winning, if rivals do in fact fear his 3rd week form, i wouldn't count on 20s being enough. If they wanted to really take him out of GC at that time for good, he'd need to lose minutes. I just don't see that being possible assuming his 3rd week form would be formidable.I don't see how his rouleur skills will save him to Sestola. Nor that getting dropped there automatically means that he won't be strong in the third week.
Again, my personal opinion: either he gets dropped in the first week, and he'll improve, but not enough to have won GC anyway (even without time he lost in the first week), or if he's strong enough to control the race in week 3, they won't put significant time onto him in week 1.