I have a difficult time with the phrase "professional." I used to think it had some meaning. Now I think it's a code word for "don't do things that the managers/organizers don't like."
Can I wear a pony suit to work and be professional? What about at DjangoCon? What about wearing shorts and sandals? In some places they are acceptable, in others they are not. Does that make them professional or not? So it seems like DjangoCon allows certain types of non-professional conduct.
Is it professional to drink alcohol while at work in most programming companies? What about taking a nap during someone's presentation? I don't think so. Is the same true for DjangoCon? I don't think so. I've done both at conferences, and people knew about it, and no one seemed to have a problem with it. I've seen others do the same.
There's another meaning of "professional", which is to do quality work, and be responsible for any errors that occurred. I don't think this is the type of "professional" that people mean. I've not seen anyone kicked out or even chided by the organizers for presenting a lousy and unprofessional presentation.
As to the coffee shop example, that can be judged without reference to respect. The goal of a coffee shop is to sell coffee. They have broad discretion as to what they think is the way of achieving that goal. This is based on property law. If they don't want you to play loud riffs at 4pm then they don't have to claim there was disrespect, only that it's unwanted, and they can use the credible threat of police response to back their demand that you leave.
The neighbors also have some say in the matter. Loud music might be prohibited, and your amp is turned up too high. Again, "respect" doesn't factor into this at all.
But for a dinner party, or for Django, I don't think it's possible to have a good definition of "professional" or "respectful." It comes down to the vague "don't do things that we don't like, otherwise we'll kick you out." Using "professional" just makes it sound more objective.