Your quoting of the timing steps of claiming the ring in resolution are entirely incorrect, because Hotaru isn't claiming a ring in resolution, she's merely resolving the Ring that you just claimed as part of resolution. But the effect of triggering the ring is coming from Hotaru's ability, not from the resolution framework.
The jade rule isn't applicable because you're not contradicting any rulebook effects.
Let's look at what Hotaru says:
Reaction: After you claim a ring during a <pol> conflict in which this character is participating – resolve that ring's effect.
So her ability is literally just "resolve the ring's effect". Let's look at the ring's effects, as detailed in the RRG:
Void: The attacking player chooses a character and removes 1 fate from that character.
Hotaru allows you to resolve the Ring's effect. So you resolve the effect, and the effect is "the attacking player does X". So by using Hotaru on defence, you are triggering an effect that gives the attacking player a benefit. There's no text anywhere that would suggest that you suddenly become the attacker (unlike on other similar cards). It's not about "only the attacker can trigger the ring", it's that the effect of the ring is very literally "the attacker does X". You are not the attacker if you claim the ring on the defence.
None of the resolution of a conflict apply to Hotaru's ability (outside of timing).
Now we've SEEN templating that suggests FFG are aware of the difference, since other effects say "As if you were the attacker", which Hotaru and Toturi omit.
I should make it very clear, I am in no way making any inference as to what was intended, but the rules for this are simple, if unintuitive. Trigger ring, ring SPECIFICALLY gives attacker the benefit. Perhaps "As if you were the attacker" was left off by accident, perhaps it was deliberate, but the reason behind the ruling is very clear because that's what follows the rules.
We've already seen from FFG if something ISN'T intended (eg, stronghold switching provinces), then despite an initial ruling that acknowledges how it currently interacts with the rules, they're willing to make changes to make things work as intended.
It's not the end of the world either way, though it does knock off some of Toturi and Hotaru's power. If the intention is for them to work on defence, I'd expect to see a change to the RRG or the cards in due course. If there's no change, then they're working as intended. I'm nothing officially to do with FFG so I'm not going to make a case either way to which was intended.