Don’t forget that there is a big chance WvA will leave the tour halfway if his second baby comes early, and in that case, he won’t be of the same value as last year.
WvA has had a slow year in terms of wins (Ghent-Wevelgem didn’t help), so he is desperate for some wins in the prime years of his career.
He is one of Jumbo’s team leaders and paid as such; he is supposed to win and he is the main marketing subject for the jumbo shops in Belgium. Saying that the GC is more important is, imho, what cycling fans think is most important, but not necessarily what jumbo management thinks is most important: after all, they already won the tour (and giro and vuelta), but they eg never won the worlds, some classics,… and Wva would be as valuable, if not more, for jumbo, if he can win those.