Pretty sure the "trivial" in the blog post is sarcastic, or at least slightly self depracating.
If I'm right in my reading, the author of the tweet is wrong to complain about them saying it's "trivial," because they never did.
For my point it doesn't matter if they are in the wrong, if it was easier than they claim, if they are rude, etc. All I'm saying is that the complaint on Twitter is that they now called something "trivial" that they said wasn't simple or easy before. They clearly didn't do that.
They said the trivial idea was a larger lookup table and Direct2D. And then they said that unfortunately the trivial idea doesn’t work. So instead they had to write their own custom text renderer, which they never imply is trivial.
Dear ImGUI also does this, and while font baking is not trivial, integrating ImGUI is almost.