Flights to US from Catania? Or?

No snark needed, lol—Your reasoning seems sound. The only other way to do it is to break up the trip by flying to any city that has connections to CAT and switch to a low cost carrier, but that requires extra time (and to me seems like more of a hassle unless a secondary stop is desired/planned).
The trip to the airport should not be an issue, just have your hotel book a taxi for you. Brutal wake up, but conducive to napping on the way home at least, good luck!

Very easy to get to the airport for a 6:00 am flight, our tour guide had the hotel arrange a cab at the appropriate and very early hour. Enjoy the tour, Sicily is my favorite Rick Steves tour so far. And November was the perfect time to go. FYI, the final day "breakfast together" is not really a formal thing on Rick Steves tours. Those who haven't dashed off to their next thing tend to come down to breakfast at their leisure, there's some good conversation and hearty goodbyes, but no formal program.

Hello,

We decided to fly low cost carrier non-stop to Amsterdam (AMS), stay a couple of nights at Citizen M at the airport and then catch a 9:30 a.m. non-stop flight home.

We enjoyed one full day in Amsterdam and had flights that we preferred. You might look into something similar --- it wouldn't necessarily need to be AMS if a different airport gives you better flight times (or sightseeing).

Do you want to fly home immediately after the tour or would you consider spending some time elsewhere?

What I often do when faced with bad transatlantic connections is fly (often on a discount carrier) to another city and spend a few days there before flying home. I often choose London. For example, if I were taking this tour, I might by a multi-city ticket U.S. to Palermo / London to U.S.. I would buy another ticket for Catania to London and spend some time in London before flying back to the U.S.

To see what cities might be options, I will start with the airport wiki pages to see what airlines and cities are options. For example, look at this wiki page and scroll down to “Airlines and Destinations”
https://en.wikipedia.org/wiki/Catania%E2%80%93Fontanarossa_Airport

with the new tariff war afoot, feel the need to lock in our travel costs now.

Tariffs are a tax on goods entering a country. Really shouldn't affect your 'travel costs'.
I doubt the hotels and restaurants in Sicily, or anywhere in Italy are buying anything from the US that would be affected by whatever reciprocal tariff Italy might impose on imports from the US

I wouldn't let the 'tariff war' determine how much post tour time you spend there.

I sometimes fly home from Catania to the Us via Munich, so you can check Lufthansa.
But it is easy to get a taxi at any hour; you should ask your hotel to order you one the night before.

Travel Service Tariffs:

I am not an authority, but please see this NY Times article (paywall removed, "gift" link) titled

Countries Targeted by -----’s Tariffs May Strike Back at U.S. Services

Subheadline: Service sectors make up the vast bulk of the American economy, which gives trading partners some clout in trade negotiations.

By Patricia Cohen, Adam Satariano, Eshe Nelson, and Jeanna Smialek
April 2, 2025

https://www.nytimes.com/2025/04/02/business/economy/tariffs-foreign-goods-tariffs-us-services.html?unlocked_article_code=1.9E4.S3mb.YpQlStL25qEN&smid=url-share