The process is more complex than it looks
Whatever they scrape they need to wash off.
The fluid they wash off is full of the elements on both sides of Si (and down) in the periodic table. None of these is particularly nice to the environment so if the technology does not retrieve them the total damage to the environment is likely to exceed any savings from using solar.
Add to that the fact that they need to scrape a relatively large surface to the depth of several micron and it all becomes a considerable technical achievement.
If they have managed to do all of that I can understand them being happy.