True, but its not a free for all. Judges (especially in a common law juridsiction) are supposed to be consistent and interpret laws following certain principles. There are more right and less right interpretations - thus we can grade judges on how well they do their job.
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”
