I consider "negative attention seeking" behavior to be behavior that is designed solely to get a (negative) reaction from another person. The person is not expressing a sincerely held point of view but rather saying or doing something for the purpose of eliciting a reaction from the other person.
Well, I was responding to a general question about the definition of negative attention seeking behavior. Behavior can, of course, be multiply determined. However, I guess if a sincere opinion is being expressed then at the very least I would probably only characterize the behavior as partly negative attention seeking, the part that is designed knowingly to elicit a negative reaction.
Thinks of it this way: If someone came to me showing symptoms of both depression and anxiety, I would probably diagnose the person with major depressive episode (the depressive part of his behavior) and an anxiety disorder (the anxious part of his behavior). One does not rule out the other.
Similarly, one might have an honest opinion and express it solely for that purpose. That would not be negative attention seeking behavior. But even if the opinion was sincere, if the person expected it to elicit a negative reaction from the other person and did so partly with that goal in mind, then I would describe the behavior as at least partly (and perhaps predominantly) negative attention seeking.