The author provides a single critisism ("The italic is mediocre"), does not elaborate, then immediately hedges their critique.
Helvetica is used as an example of a font which garners more "affection" in contrast to TNR, but is never praised by the author or recommended as an alternative - at least not in the linked passage.
The author also criticizes the narrowness of the font (and particularly of the bold style). They're not trying to argue that Times New Roman is terrible - just that it's substandard.
As a body copy font, sans serif is generally seen as "friendlier" and more casual--which is one reason you see more of it than you used to in marketing copy and many other uses. Friendly and casual are generally not things I'm looking for in legal documents.
Helvetica is used as an example of a font which garners more "affection" in contrast to TNR, but is never praised by the author or recommended as an alternative - at least not in the linked passage.