offensively stereotyped = offended against (in a conventional manner)?

[NewHopeR]

The definition the word "stereotype" is obvious:v.
treat or classify according to a mental stereotype
It is first time that I encounter such usage. Post this thread to try to get a stronger impression.

Context:

This article has drawn an extraordinary level of outraged response. The volume of comments has been so great that our online commenting system is unable to cope: it deletes earlier posts as new ones arrive. We much regret this ongoing problem. The disappearance of some cogent responses to the story has fuelled suspicions that Nature is deliberately censoring the strongest criticisms. This is absolutely not the case: Nature welcomes critically minded discussion of our content. (We intentionally removed only a few comments that violated our Community Guidelines by being abusive or defamatory, including several that offensively stereotyped the many Chinese readers who commented on the story.)

[JMurray]

…including several that offensively stereotyped the many Chinese readers who commented on the story.

In this case:
to stereotype = to describe or label a person or group in a way that is overly simple, often derogatory and based on prejudice and/or ignorance.
Therefore "offensively stereotyped" means to refer to people in this way, to a degree that is particularly offensive.

not a teacher

[5jj]

You'll probably get a stronger impression if you look through the 664 citations for 'stereotyped' in COCA.

[NewHopeR]

You'll probably get a stronger impression if you look throuugh the 664 citations for 'stereotyped' in COCA.

An excellent source for enhancement.