While this may not be the ideal behavior, there doesn’t seem to be a good alternative. Updating the node documentation panel while you’re dragging the rubberband would be a CPU-intensive task that would potentially make marquee selection sluggish. We recommend the workaround that you suggested of clicking on the node.
The conflict I see is that the same state (a selected node) has different behaviour based on how it got selected, which breaks the model.
I could see a case to not update in realtime whilst selecting, and of course there’s no support for multiple selections.
Here’s my thinking: on mouseUp, if one node is selected, show the node documentation for it.