that equation is simplified for a specific case and assumes that you are keeping altitude constant. in a gliding situation, (also in an ag turn) you are not keeping altitude constant so load factor will not increase that much and therefore stall speed will not increase by that much. remember stall is related to critical angle of attack only, and has nothing to do with airspeed. the only time stall is related to a particular airspeed is when you maintain a constant altitude.

when you maintain a constant altitude, lift is held constant so you reach critical angle of attack at a particular airspeed. in accelerated flight, you are producing more lift so you reach critical angle of attack at a higher airspeed. when gliding, lift remains constant so stall speed remains constant. the horizontal component of lift is bought at the expense of altitude so that you can maintain L/Dmax speed.