Huh? Alaphilippe was with him until Krabelin. What more did you expect?
He was dropped on Krabelin from the moment anyone started to put in some effort. We are talking about Alaphilippe here yes, a guy that has been able to survive such climbs (Civiglio for example) to race to a top-5 himself. Now if he was on a bad day, it can happen I don't know. But a motivated Alaphilippe that is riding for his own GC or chances has done better on tough climbs before.