What is the "dignity" that delays for all?
In Emily Dickinson's poem (named by its first line) "One dignity delays for all", the last dignity which one has is that of a proper funeral. Dignity is a state which is worthy of respect. Therefore, a funeral is a procession which demands respect from all, regardless of knowing the person or liking the person.
In death, all of mankind is made equal. Death is a fate all of mankind must face--regardless of wealth, status, behavior, or character. In the end, all men and women die. It is during this final stage in life which all must, or should at least, respect the dead.
That being said, in death, all men should be dignified. It is the final "stand" one has on earth, the final "walk" one will take, the final act of mankind.
In regards to the delay which dignity has, some men/ women may not deserve to be dignified in life. Regardless of this, one should always respect death and act with respect to the deceased and their dignity.