Here's another thing though - I don't think there are such things as genuinely weak rebel mages. I think that mages that would feel like they are too cowardly or inexperienced to fight and if they were too afraid to die, they wouldn't join the rebellion.
Where's a mage to go to? Leave the rebellion, they leave themselves exposed. Turn themselves into the Chantry? That... may not work well. They could hide, and with the phylacteries destroyed maybe that'll work, but what if some templar walks by, or they don't want to abandon their mates?
Many mages didn't want to rebel, they did by an exceptionally slim margin, but it's not like there's much else to go. Redcliffe was one place that offered safe haven. It is, in all honesty, not the best time to be a mage.