Sage Advice 3/21/16 Exploding druids and antimagic field vs zombies and cure wounds

The answer to the druid and metal armor is excellent. Not so much the ruling itself, but the clear way it explains that classes have both story and game elements, and some classes have more story elements than others.

 

[77IM]

Vegetarians don't eat meat. They can eat meat (in the sense that they are physically capable of doing so). But if they do, they can't call themselves vegetarians.

That's basically how I see druids.

Druids don't wear metal armor. They can wear metal armor (in the sense that they are physically capable of doing so). But if they do, they can't call themselves Druids.

So if a Druid voluntarily wears metal armor I think it's up to the DM and maybe the player as to what that means.