...stepping on an unsupported rear triangle? Dropping heavy dumbbell weights directly on them from 2 feet off the ground? Going at them with an angle grinder? That's not real world testing.

I've toured some, back in college, and mostly I've ridden and raced road bikes over the last several years. A couple notes on that. Racing is much harder on equipment, in my experience, than touring. You have a lot more things that break from traumatic stress, as opposed to prolonged fatigue. Though the miles a well-trained racer needs to put in means a lot of fatigue failure as well. For the day to day knockabout stuff - as you cited, stepping on bikes, hitting curbs, lamp posts, whatever - that a road or race bike is subjected to, carbon fiber is well-proven to be more than durable enough. It does have some specific weak points, which are pretty easy to exploit if you want to make a video to scare people away from it, but those weak points are mostly not relevant to what a bicycle is actually subjected to. If you regularly park your bike in an angle grinder factory, I guess steel would be safer, but when I see broken carbon fiber it is usually because it's been involved in a violent crash. That's a bummer, sure, but my steel race bike has a dent in the top tube from a fairly mild crash where the bars swung around and hit it. I've seen worse crashes that left carbon bikes unscathed. The carbon fork on my race bike has never been a problem. I did have a steel fork fail from fatigue and rust, once. What does that prove? Almost nothing - it was an old bike. Except that steel certainly isn't invincible. Give anything enough time and enough stress, and it will break. Some things sooner than others.

I don't think touring puts identical stresses on equipment, but my experience is that it's just not as hard on a bike as racing is. My biggest concern would have to do with contact with the fork. That is, while I would be okay with clamping a rack to a steel fork without mid-fork eyelets, I wouldn't recommend this with a carbon fork. But a carbon fork with mid-fork eyelets wouldn't cause me to bat an eyelid. I've ridden the carbon fork on my road bike very hard for thousands of miles over all kinds of surfaces in all kinds of conditions. Carbon fiber is more than safe enough to handle touring. A fork designed specifically to mount a front rack in particular.

Regarding whether or not paring down weight by 1 lb is worthwhile: if the original fork was undamaged, maybe not. But the OP should probably replace the fork regardless. The additional cost to go with carbon fiber isn't outrageous, and reducing weight by choosing lighter parts on the bicycle can go along with reducing weight by packing lighter. They aren't mutually exclusive, and every pound saved counts.