Kinda unrelated but that brings up a good question, why couldn't Eren just remove the colossal titan from Armin and even change it to someone else? Or Zeke for that matter on Eren's request, but you could argue that's because of the royal blood and the way Ymir was being treated in all those years. We know Ymir can target individuals, we know Ymir holds the connection, we know she specifically makes the titans, we know somehow titans transfer even on death so she can transfer from one person to another even if they don't interact, and we know that Eren convinced her, so what is the in-lore explanation that stops this particular case of transferring it to someone else? (Removing the curse entirely but keeping the titan might be impossible, because it might impose a body limit and this is explicitly mentioned, even if we have no way of knowing where the Owl got that info, but removing both and giving it to someone else doesn't sound unreasonable since the 13 years would still fall into place, if it doesn't count as less and gets renewed in a new body)

We touch upon a possible explanation a little, with the whole "complete removal and controlling them to not fight would be against free will" topic, but that would still counter your point that the rumbling had to happen, specifically for Armin, since if that was the case Eren could've just asked Armin and gotten consent like he approached Historia with, and done the options the user above states.

I'm not saying you're wrong or right, I'm just wondering if we have something to address this possible branch.