Hi Adeline,
He values honesty and trust when it comes to relationships. To him, someone who isn’t forthcoming with their baggage is hiding something.
That makes it harder for him to trust the person. To him, the lack of honesty and trust is a deal-breaker.
Using baggage as a litmus test is how he goes about filtering potential romantic partners. It doesn’t mean it’s right. It is just how he sees it.