Dmitri is a lord and expects to be treated like one. He places the safety of his village above the welfare of strangers. He has seen adventurers before and assumes that the characters are Strahd's allies or enemies; either way, their presence spells trouble for Krezk. Dmitri isn't prepared to shelter Strahd's enemies any more than he is willing to humor Strahd's allies. The only way the characters can earn his favor is to help Krezk in some way, whereupon Dmitri is required by his oath of office and his honor as a Barovian noble to show them hospitality.