Yes and no. A policy of overwhelming force is more effective if your metric is a binary peace/no peace. However, when it fails, it fails catastrophically, and you find yourself in a war that you do not think was anywhere near worth starting.
Both the US and Iran are being very restrained at the moment, and no one wins if that changes to both sides going all out. In fact, from what I can tell, both sides are being dragged into this conflict against their will.
Plus, the US has other concerns. There is still a war going on in Ukraine, where, as far as I can tell, US support is much more vital to US security interests. And there is the evergreen spectre of a war in Taiwan that the US needs to maintain posture on.
Not nessasarily, the protocol could be written so that an instance simply tells other federared instances "X of my users upvoted this, and Y downvoted this".
The tradeoff being that instance then have less tools to work with to moderate voting. Instead of being able to do global vote ring detection, the most they can do is look for abuse on their own server, and trust that every instance they vote-federate with does the same. Even then, with every instance trying to be vigilant, no one instance would have the info to detect a cross-instance abuse.