Please explain the statement "Photographing someone without consent at a conference is really not minor."

PyCon has no prohibitions on taking photographs, and neither does the venue. Taking pictures in public without consent is legal, with only a small set of exceptions. PyCon by default inherits those rules, so I don't see how it's illegal. Perhaps have some moral code in mind?

Here is a picture of people at PyCon 2013. http://www.flickr.com/photos/brianly/8583308663/ . Do you think the photographer got permission from each of the people to take the picture?

Here is a picture of Michael Foord and Guido van Rossum, where Foord's name tag is clearly visible. http://www.flickr.com/photos/brianly/8583315245/ . Here's one of Shane Grigsby http://www.flickr.com/photos/brianly/8584459432/ , with name tag clearly visible. Do you think the respective photographers asked for permission to take the photo first? I doubt it, but it might be possible for those specific cases.

I have taken many photographs at PyCon over the years, without asking for permission. Many photographs were taken of me, including this one http://www.flickr.com/photos/uhop/400449848/ while I was speaking. I never granted Uhop permission to take the photograph. Under what basis do I have for complaining that it was illegal, immoral, or unjust for that photograph to be taken and published to flickr?

I agree with "is really not minor" only if by that you mean "perfectly acceptable." However, I don't think that's what you mean. You imply that it's a serious ethical transgression. I don't understand how, so I request enlightenment.