Isn't there a door that would be closed between the vestibule and church? Or is it too thin a door? Whatever the case, you were absolutely right to ask those people to show some respect and consideration. As for the deacon...I've seen pastors carrying on with select parishioners INSIDE the Church before Masses.
Respect and common courtesy are two things that have been going the way of the Dodo bird for quite some now in all facets of society.
When I finished my after Mass prayers, the people who were still left were in the vestuble, so I did end up closing the doors.