That's how I see it, also. Even if the initial attack lit stuff on fire I would look at the damage from the fire, if it's fully suppressed then so is the fire.
So, is the torch or lantern also protected? (It's part of your attended gear, after all.) If so, can you light it?
And if you can light it, will it ever burn out? (A Torch does a D3 of fire damage, if used as a weapon, so it can't penetrate even the weakest Energy Resistance).
This is the aspect that makes it silly: Either you can't ever carry a lit torch, or you can carry the same lit torch forever.
And I wonder why we don't see naked Fire Giants running around? Their personal immunity is natural, not a spell, so it wouldn't protect gear like the spell, would it?
By the way, this particular silly thought is based on an equally silly (and peripherally related) situation in 4th Edition.
4e has a specific "condition" for being in fire. By those rules you and your gear take damage every round you're burning, on your action. The silliness comes into play when you consider unattended items: They don't get actions, so by the rules they'll never take any damage from the "burning" condition. So your campfire will burn forever, unless someone is attending it. And the torches in that ancient temple, the ones that were lit when you came in? There's nothing magical about them, even though they've apparently been burning for thousands of years. They just haven't been held or carried in all that time, so they never take any fire damage and so they never burn out.
As a final bit of silliness on this: Our group recently had to face some Frost Giants. Now these guys are CR9s, so for a Level 15 party they're speed bumps. Their leader, however, was a Frost Giant Jarl right out of the book. And also right out of the book is the Ring of Fire Resistance, 5 points, that he wears. Even though they only come in 10, 20 and 30 point varieties because that's how the spell scales with levels.
So now our party has that oddest of items, the magic ring that no one can reproduce, because it's too low powered.
What's your favorite silly rule? (The
Resist Fire one is fun, but my favorite is that trees are immune to
Disintegrate because they are neither living creatures nor noliving objects, and those are the only classes of things the spell describes damage for.

)