We are all getting far too technical here! Look at what Babe's question was. The answer is that IF the senior is unsure of what is happening then either the Captain, Senior, or deputy Captain (F/O) need serious re-training. The sad fact is that given the 'wrong stuff' up front it COULD be a serious situation and they just are not saying. However, the senior would probably already be aware of that sort of personality.
A hackneyed 'TLA' I know, but it is called 'CRM' - and it works both ways through the door. I CANNOT conceive of a situation where my senior would be left in any doubt. To amplify Hand Solo's post - if there is no NITS brief, there should ideally be a face-to-face 'chat' up front or an interphone explanation. If for any reason I had left him/her in doubt, I would expect then to ask.