It’s become my experience that what often passes for moderation (political, personal, religious, etc.) is actually measured restraint. That is not to say that there aren’t true moderates, or moderates of convenience, but exhibiting a measured temperament and sensibility is typically where people see the value of moderation.
The argumentum ad temperantiam can then be avoided while embodying what it values. In other words, the biblical virtue of self-control is the virtue of being measured, which, as it happens, often looks like moderation.