Sorry, I don't understand your reasoning.
If we assume that all altitudes in the graph should be shifted up by about 175 feet, and adjust the graph accordingly it shows a somewhat different pattern.
Why assume an altitude correction of 175 ft to the data when the QNH implies it should be 378 ft? Looking at the actual position of the last "-200 ft" data sample and comparing it with photos it looks quite probable that the airplane was still airborne at that point, possibly even at +178 ft amsl as the QNH corrected data suggests. And with a -4096 fpm descent rate it would anyway have reached ground level in ~2.5 seconds.
The conclusion of the above would be that the airplane remained on or above the glideslope for an even longer time.
Anyway, bearing in mind all the various measuring inaccuracies I would not dismiss the possibility that this much discussed -4096 fpm descent rate may turn out to be sampled at precisely the moment when the airplane's nose slammed down in the field, accelerated by the moment around the main wheels, as explained in earlier posts. But let's be careful not to make too deep conclusions from this unofficial data.
PS: From the looks of it, the position of the last data sample seems to be around 120 m short of the actual location where the nose came to rest. Corrections welcome
