Just right  

is actually both an attacking move and a defensive move. It is a three space pincer (attack) on on the right side and also an extension (defense) from the lower right starpoint stone. It is somewhat loose in both senses, but still it is simultaneously an attacking and defensive move. It is a dual purpose move.

Sonoda's "don't enclose" also might mean don't just enclose. Territory-enclosing moves are often fine if they also attack the opponent, following the classical advice "make territory while attacking".