That is pretty bold of them to ask you to leave.  I can see their point of paddling around to let you know they were camped nearby so that you might choose to camp somewhere else, but I wouldn't have gone that far.  I have had groups camp nearby and it does irk me a bit in Quetico, but I have not asked anyone to leave.  In the BWCA crowds are expected, but I like some solitude in Quetico.