I don't think anyone is missing the point
The article states clearly that they are using a neural net to to fill in values for a defective sensor (MEGS-A) - this makes the values "fake".
It is true, NASA has a large collection of complete (and, we hope, accurate) data from before the sensor died. As a general rule, it is reasonable to assume there is a strong predictable pattern across the entire spectrum it is monitoring. As a consequence, inferring the missing data is reasonable - just as we would expect to filling any missing data for a reasonably understood phenomenon (say black body radiation).
If the only reason for the satellite is to accurately monitor the sun, and the spectrum is fairly standard / uniform (the way black body radiation is), then missing the lower third of the monitored spectrum (5-37nm) isn't a big deal. The entire spectrum studied is 5-105nm.
If the reason for the satellite is to study spectrum because we don't understand it well - because it is highly variable - then interpolating the missing 5-37nm becomes problematic.