"Whitewashing" is a reductive, but convenient, term to describe a process that is more complex than most people think. To explain in more detail:

The most simple form of 'whitewashing' is just broad reputation laundering, that we're all familiar with ("Ackchually they weren't that bad!" brand holocaust denial, or justifications for future actions based on unfair treatment in the Treaty of Versailles etc.) but more commonly, and much less obviously, it's used to single out a group of "bad apples" or similar that were responsible for the majority of the "bad", and then exonerate (by lack of inclusion) those people who were not part of that "bad apple" group. Look at the initial comment for a more blatant example of this:

Some German officer was actually investigating these crimes (abuse of prisoners in the camps) until the Nazis dealt with him (can’t remember his name though).

They present this idea hand-in-hand with the idea that to a degree that is significant enough that it bears mentioning German officers weren't okay with the holocaust! They were even investigating it, until they were silenced by those darn Nazis! (Conveniently we don't know who this was so we can't check into this). This ignores that any "german officer" would have had reams of proof of all kinds of the nazi's crimes available to them in the form of SD reports, which were not in any way an uncommon resource (most officers would have had them delivered daily), so the "investigation" would barely have been necessary. But by having this hypothetical officer investigate it, the potential for exoneration of everyone that weren't the "Bad Ones" is created.

This the same idea as I was talking about before - by presenting the Nazis as having taken over "illegitimately" it implies that there was a legitimate government that was opposed to them, an implicitly significant group, and thus leaves open the possibility that people were just part of that illegitimate takeover and weren't really "Bad Guys", the first country the Nazis conquored was Germany, after all!

... But they were a legitimate government. And claiming they weren't needs to ignore things like the fact the nazis came to power in an overwhelming (44% of the vote!) democratic victory, and then maintained that huge public support (even higher, actually) right up until the end of the war. The average german knew about this, supported the nazis, and none of the horrifying shit they did was illegal under german law.

I don't think the initial commenter did this intentionally, judging from their post history, but I do think that in their eagerness to contribute on a subject they very clearly are uncomfortable making strong assertions about, they wound up repeating Nazi propaganda.