Then the proxy war is one-sided, and we need to challenge Iran in a hot war.

Most proxy wars are one-sided. That doesn't support starting a hot war with Iran.

The Houthis are harassing commercial trade in the Red Sea. We want them to stop, because that harms US interests.

But a hot war with Iran also harms US interests. It would destabilize commercial trade in both the Red Sea and the Gulf to a vastly far greater degree than anything the Houthis are doing. We're not going to invade Iran itself - we're not even willing to invade Yemen to make this stop.

So what would be the military aims of the hot war with Iran? What would we be trying to accomplish? What would the cost of achieving those aims? What would be the consequences for the region?

We wee folks on a message board don't know the answers to those - there are lots of people who have trained their whole lives on both the US and Iranian sides to figure out the answers - but those are the questions that are relevant to whether Iran would heed a US threat to sink an Iranian flag vessel in international waters. I think Iran has correctly assessed that a hot war with Iran is so detrimental to US interests in the region that we wouldn't follow through on such a threat. Regardless of who the President was.