The potential possibility exists. I am friends with one of the top promoters and teachers of Reiki in the U.S., someone who travels regularly to Japan to confer with the Japanese originators of the practice. (And we don't "avoid the subject.") I have other friends who are developmentally disabled and don't have the ability to learn to count to 20. I focus on the great deal we have in common and am respectful of what we do not.
My Reiki Master friend does not require me to believe in her practice, nor do I require her to share my doubt, as a condition of friendship. I don't require people to be able to count to 20, or to not genuinely believe in Santa Claus at the age of 45, as a condition of friendship.
But with truthers, it's not that easy. Critical thinking is above all a tool that facilitates trust. Those who lack it use other less effective trust models instead, such as trusting everyone (which, besides being unsafe, requires them to overlook contradictions), trusting the first thing they hear and then denying all subsequent contradictions, or trusting and distrusting based on arbitrary and unreliable criteria such as race, age, or religion. Truthers are among those whose flawed trust models preclude their trusting anything anyone says on any evidentiary basis at all. That's why they can confidently dismiss all expertise no matter how legitimate and well-demonstrated, treat ordinary people who disagree with them as willful liars and criminals, and turn on one another at the drop of a hat.
Only under very extraordinary circumstances would one be friends with someone whose behavior toward you you consider criminal -- such as someone who repeatedly steals from you or assaults you. When one doesn't believe in 9/11 trooth, you become such a criminal in truthers' eyes. Other than believing in their nonsense, there is simply no way to earn a truther's trust. Which I would say makes all but the most tenuous and unstable of friendships impossible, and explains why we often hear about even longstanding prior friendships being broken as a result of one of the friends becoming a truther.
Respectfully,
Myriad