As far as I can tell, this doesn't change when the actual orbital transfer from earth to mars occurs, it just allows launching outside the normal transfer window and then loitering until the window arrives. In this case, what benefit do they have from launching it now and loitering for a year rather than just launching it a year from now?
Because of the lowered cost of launching on this particular New Glenn. By the time of the next window BO will be able to command more money for a less-risky launch.
It might be better budget wise, especially in volatile times