Dude gets excited about trains. More power to him, I say.
Some context: trainandhawksfan17 is a foamer, aka a trainspotter, a railfan, a gricer — in other words, a person who likes to watch trains. And kudos to him for fitting both of his interests into a single username.
According to a commenter at reddit, here is some background on this particular locomotive: “These heritage units are a fleet of special SD70 locomotives painted similarly to locomotives from all the major railroads Union Pacific bought/merged with. Their paint jobs are very well done and reflect the railroads they represent very well. There are only 6 of them, which makes them very very rare to spot. They do circulate around the country though, as the SD70 is one of the cross-country locomotives that hauls freight from one side of the continent to the other. Here in CA they’re not hard to catch at all. But I’d expect that they’re very hard to find in places up north or in the midwest. Hell if I lived in the middle of America and saw one of these I’d be running up and down the street as well.”