Perez doesn't belong in Formula 1: Do Red Bull still have the receipt?

Missing Q2 (again) during qualifying for the Canadian Grand Prix is another low point in Sergio Perez's career. The Mexican is simply not good enough for Red Bull Racing, he has demonstrated not for the first time. Indeed, Perez is not good enough to have a place in Formula 1 at all. When will his employer (read: team principal Christian Horner) see that? Would Red Bull actually still have the receipt, to still get out from under that silly, two-year contract with Perez?