It isn't fair!! You're right.
The primaries are designed to help each party select it's strongest candidate.
(Unless it's like Georgia, where one party deliberately crosses over to get a weaker candidate for the other.)
In the case of New Jersey, clearly the Democrats have to go without their strongest candidate, the fellow who won the primary. That isn't fair.
It would take a pretty weak Bankrupter to lose to a weaker Democrat. I mean, the Ds have one hand tied behind their back. The Bs would prefer two, though, wouldn't they?
Arf (and they still whine!! Go figure.)