I am definitely not a rules expert, so it bothers me, too, because I have been in a very similar situation where I was PL. PW was yelling at me for room to pass behind the starboard boat. I'm thinking, "What the heck is that about?", because PW had plenty of room to tack to avoid the starboard boat.
In my case, PW also had plenty of room to pass behind the starboard boat anyway, so did not need to yell at me for room. However, it has been bothering me ever since, because I just didn't understand the hail by PW. <img src="http://www.catsailor.com/forums/images/graemlins/crazy.gif" alt="" />
It might make some sense if there were another boat close above PW making it impossible for PW to tack (in which case I would think that "other boat" to windward would actually be the "obstruction), but that was not the case in either situation.
Maybe somebody can explain this to us. <img src="http://www.catsailor.com/forums/images/graemlins/tongue.gif" alt="" />