Ol' Homer actually has an answer for you. Here are two answers to your query -- you select the one which you want to believe is the correct one.
A. The street was named for Joe Marginal who was a first ward politician or;
B. During the late 1950's when the construction plans were being drawn for the Route 80 / Hudson Street exit, an engineer wrote the words "Marginal Road" on the construction plans since that right of way had not been named. The plans indicated the designation for a marginal road which ultimately was shown on the City's street maps as "Marginal Road". And the rest is history.
Sorry Joe.