Re: [WHY ARE WE HERE]
I'll grant you the time limit. I'd strongly prefer to have our hands on more keystones before we act, enough to strike decisively and all at once. But I can see your point if it's a choice between that and letting her out into the multiverse.
We have a single incident. That's not a precedent, and circumstances have changed. If they're at war -- I knew Queen was moving, but not that King had responded -- then we need to take more explicit advantage of that to hide our tracks, rather than just hoping our enemies will assume what we want them to.