I think the second paragraph is. They are saying that an "error" is any departure from legal principles, and the poster is saying that that is a bad definition of error.
It doesn’t say anything about legal principles or consistency and it mentions that “errors” may only be departures from a surface level understanding.
“ Such departures, however, may not always reflect true lawlessness. In particular, when the applicable doctrine is a standard, judges may be exercising the discretion the standard affords to reach a decision different from what a surface-level reading of the doctrine would suggest”
