This scene is doing its best to argue that Syr’Nj and Byron have not just become a pair of idiots for the convenience of the plot. I think it’s partly successful in that: Syr’Nj’s precaution is reasonable, and Byron’s musing that this could be all about him makes sense, given how much time he’s spent recently as the leader of a larger movement.

It’s somewhat sketchier how Syr’Nj expects Byron’s team to be able to disrupt a soothsayer’s plans, and if disrupting predictions is the name of the game, why not have Byron not go? They could send him to help Frigg’s team instead, and surely Syr’Nj could pop in to explain the last-minute personnel change. It’s true he knows the Cultists better than anyone else, but c’mon, how much do you need to know about these guys, they want to destroy everything and use magick to make you want that too, that’s pretty much their deal.

But… even though Bandit is the field commander of the Peacemakers and thus a general authority, Byron is still the leader of the movement and the focus of its morale. His presence could cause a massacre, but so could his absence. Moreover, as much as he wants to be rational here, to be outwitting the Cultists, to be more than the Berserker, he’s driven to confront them regardless of warning signs, a fact that will become clearer as we go. (“Certain doom” is an, um, interesting turn of phrase… maybe an attempt at tension-breaking humor, but still.)

Syr’Nj knows all this, and knows that taking him out of the field against his will (“Here, try a little of the extra-strength anti-berserk now… oh, sludge, it had too much sedative in it, guess you’re staying here!”) would be a breach of trust from which they might not recover. “You’ve made your choice.” Marching into danger constantly is what adventurers do. So she elects to trust his instincts and hope for the best, a choice she will later regret.  So maybe they have become a pair of idiots, just a little bit, but in what I hope is a mostly believable way.