I don't think muscling in on a singer's performance is a moral question, unless and until they have been told in a very straightforward manner that this is not the local practice, or is not what the performer wishes etc. They don't know. Just like people don't know exactly the way obsessive people like to load the dishwasher, but will always get it wrong unless they are told the preferred way. We are talking about personal preferences, which are not universal, cultural differences in a time of great cultural diversity even in out of the way enclaves, and wierd assumptions that strangers to an event are somehow supposed to know what the unspoken rules are. Just say what you prefer and kick them out if they don't comply. They don't, the poor simpletons, know that it is not right or proper to do certain things. They probably eat peas on their knives besides and blow their noses on their shirtsleeves, which is why Napoleon supposedly came up with buttons on sleeves, but that is another story altogether. mg