Six at the beginning is a reading for somebody who is ready and has not been asked. The line puts the wish to advance and the fact of being held back in one breath, promises good fortune to firm correctness, and then addresses the harder problem directly: if trust has not been given, keep a large and generous mind and no error follows. The commentary is precise about the cause, which is that no official charge has yet been received.
A querent here is usually not being obstructed by an opponent. They are simply not yet appointed, and the distinction matters because it removes almost every action that would otherwise suggest itself. There is nothing to push against. The stroke is yielding at the foot of the earth trigram Kun, and the text keeps it there, asking for correctness held alone rather than any demonstration mounted to convince somebody.
When the line changes, the lower trigram Kun becomes Zhen and the figure becomes Biting Through, King Wen 21, in which an obstruction between the jaws is removed by one decisive bite. That destination names what this line will not yet permit. Something is in the way and will eventually have to be dealt with sharply, but a person without a charge who bites first is the one who ends up in the wrong, which is why the counsel here is generosity instead.