One would take the Vuelta win for sure, but neither is a given. One could always make such assumptions and thus never go to the Tour. At the end of the day I believe a little sickness should not derail the whole season and therefore he should make the adjustment to go to the Tour after racing just 9 days at the Giro.Grand Tours count. So do WCC and monuments.
So, even if you want to discard 1 day races, would you value a 6th place at the Tour over a win at the Vuelta?