I don't think so. I think the speed window can be closed while you are in on-approach logic, although it is not something that is normally done because at that point you would want to be in speed intervention. The speed window, however, cannot be closed while doing an ILS.
If you are outside the course fix in ALT on a VNAV approach, you are usually not in on-approach logic until crossing the CF. So when you select VNAV 2 nm prior to the CF (sometimes we will start VNAV from the CF instead of FF), the window will close and the aircraft will usually accelerate. If there is a lower speed entered or coded at the CF, it will prevent this sudden thrust surge when the window is closed.
Also, if you extend the centerline from the FF, I don't believe on-approach logic would start until the FF. So you would also get the thrust surge between the CF and FF if you extended from the FF.