Well, firstly, you will probably be on your way through the glidepath, as opposed to "on" it.
If you just increase the throttle without adjusting the attitude, you will begin to depart upwards from the g/p. The speed won't change too much. If you change the attitude until the speed is correct, then apply the correct amount of power, you should stay in the two corrrect parameters
However, I am not an A1 QFI and am perfectly willing to be told that this is incorrect...
To keep this discussion "on thread" I should say that, as far as I could tell, the "advice" on the excerpt was being delivered on the approach to land.