This has (as most other things) been discussed before.
And as in that thread, I pointed out that "the rest of the group" do not have authority over the one who deviates from their group think. Only their Inquisitor does.
While I used the example of Psyker persecution, the argument is valid for anyone in the service of an Inquisitor. I quote the most relevant bits for your convenience:
"Then there is the issue of authority.
To put it shortly: they don't have it. Unless the acolytes Inquisitor has stated unmistakably that he wants his group to police the Psycher, and given them authority to terminate him upon suspicion, the acolytes do not have authority over the Psycher. All they can, and should, do, is to report their suspicions to their Inquisitor or superior in the chain-of-command.
No organization can exist where any member can exercise total authority, arbitrarily, on one of his peers. An officer in the army has no authority on other officers parallel to his own rank. He ONLY has authority over those BELOW him in the chain of command. You can't fire your co-workers, only your boss can do that. Even in a flat organization with no chain of command (like a doctors office with a few doctors in partnership) one person cannot exercise authority over another; decisions and disputes are settled by agreements, negotiations or by a board of executives.
In the 41s millennium, an Inquisitor cannot execute another for heresy. He has to bring him before a trial, a tribunal of his superiors in the Inquisition. Similarly, Acolytes cannot judge or execute each other, no organization could exist where such judgements were possible.
Psychers are a valuable resource. The rules of the Imperium dictate that Psychers not be burned as witches, but turned over to the Black ships. No Imperial authority is going to take kindly to servants who squander this resource! Killing a psycher is only really permissible when and if he poses a clear and present danger to the mission or the group, and he cannot be subdued with non-lethal force.
A summary execution of an Imperially sanctioned, Inquisition-serving psycher would be a transgression of an acolytes authority, a violation of Imperial Law, and an insult to his superiors who cleared the Psycher fit for duty, including his own Inquisitor.
Such an execution then, would be murder! Murder of the servants of the Imperium, especially that of the most Holy Inquisition, is Treason. Treason is the worst form of Heresy."