What I like best about basing authority on concern is that it allows a tester to retreat from a position without establishing precedent. The tester can decide that the concern expressed in a bug report has been heard and then withdraw it because there are more important issues for everyone to deal with right now. The concern still exists, and may be expressed again in a similar situation if prudent.
Testers who base their authority on correctness don't have this flexibility. When their authority is based on being right, they have to defend every bug report they write. They get a reputation for being argumentative, unyielding, and unable to differentiate critical issues from minor ones.
Best is to have the ability to base your authority by either means. Start by focusing on concern. Establish collaborative relationships with the programmers. Understand their concerns and use your testing to determine where their weaknesses are. Most programmers will welcome this kind of engagement, will realize that you're just trying to make their work look better, and will appreciate your perspective.
But some will still resist. And for these you'll have to double-check your results and standards so that you can establish whether their work is correct or not. Does it stand up to the claims that they've made about it? If they are going to put up obstacles, you're going to have to overcome the obstacle course.
So how do you establish your authority? What kind of reaction do you get from the programmers whose code you test? Do you think you could benefit from an approach that balances correctness with concern?