I'm as critical of the US as the next person, but that is just a ridiculous statement. What the US does and doesn't do militarily with regards to the Houthis has nothing to do with what they can and cannot afford. Any limits on their actions against the Houthis is purely down to political will and strategic interests, and obviously not financial limitations. Push comes to shove and we all know that the US military could count on being backed up by more financial muscle than any military force on the planet (with the possible exception of the Chinese).