Quite apart from the fact that that's a reasonable number of the Templars who are given actual personalities instead of being faceless and includes one person in authority, this potential threat isn't limited to the mages. Mundanes could be lynched over anything an uneducated peasant could mistake for magic, and this isn't a small list of phenomena. Besides, they're trying to do the Templars job for them with this, and risking their lives in the process if they find someone who isn't in the Circle and legitimately ought to be. If for instance, a lynch mob found Caladrius, he'd probably juggle them.
Mage Warden: I thought all templars liked killing mages?
Cullen: I know some templars who discuss such things with glee.
Anders: You can't do this! King Alistair allowed my conscription!
Ser Rylock: The Chantry's authority supercedes the Crown in this matter.
Kerras: The Knight-Commander has been appealing to the Divine for the Right of Annulment. Finally we can show these robes a thing or two.
Thrask: If they have not surrendered by the time Kerras arrives, he'll kill them without mercy and Knight-Commander Meredith would consider him justified.
Templar from Asunder: *holds Rhys by the throat* You will Confess.
Rhys: And if I don't?
Templars: *squeezes his throat* You will die. (forgot the exact line, but it's pretty much this.)
Yup. There are plenty of examples of templars being stellar examples of caring for mages and trying to keep them from being killed by the world because it's part of their duty...wait....
Hawke: Why should I help you annul the Circle?
Meredith: The people will demand blood!
No...they don't. There are far more examples in the game of the opposite being true.