I think so. Fire resist wine is a higher order of protection than root armor's order of weakness. If I remember correctly too, the equivalent level of resistant overrides the same level of weakness. so:

Weak to fire vs Resist to Fire: Resist Wins

Very Weak to Fire Vs Resist to Fire: Very Weak Wins

Very Weak to Fire vs Very Resistant to Fire: Very Resistant to fire wins

Immunity overrides everything.

Test in a campfire to be sure though, because if I'm wrong, it's an instantly fatal mistake.