Considering I'd never heard of him, I'm kinda thinking Tony forgot about him.

Also, I thought there was something around like 2000, 2001, that kinda stepped all over the legacy of Yinsen; but continuity feels like it's going the way of the dinosaur. Iron Man continuity, anyway; so I don't have a good feeling for this fellow. From 2014, Iron Man Annual #1, "Two Cities" Written by Kieron Gillen, pencils by Alvaro Martinez, inks by Raul Fernandez.

Sigh. I'm not going to be able to track it down, but I swear I saw somebody on Twitter complaining about this storyline the other day: Tony makes a discovery of a new metal from the moon, "phlogistone," or "moon mercury." It could be an energy source that would change the entire planet...so, of course, failure is the only option: Iron Man wasn't going to be allowed to change the Marvel Universe that radically. Tony had been playing marshal to the various interests working the new moon gold-rush, which included Soviet robot Udarnik the Shockworker. It had been launched up there in 1972, and over the years built a city on the moon, powered by phlogistone. (I don't think any of them were close to the Blue Area of the Moon, if that's still there? I could use a map of everything that's happened on Luna.) Unfortunately, there was a problem: Tony discovered exposure to phlogistone caused degenerating brain problems, like the hallucinations of Yinsen he was having. Eventually Tony had to disable Udarnik, and render the phlogistone inert; and everyone went home since there was apparently nothing else to do on the moon.

Tony repaired Udarnik, who understandably was still a bit sore since now he was alone and his city powerless; but Tony has a bigger problem: he was still contaminated by the phlogistone, hallucinating and dying. Tony asks Udarnik for help, explaining he might not get what he wants now, but maybe eventually. Then he falls into a very cutting nightmare, as Yinsen berates Tony for being (metaphorically) heartless before his injury and Yinsen's death. Tony succumbs to the darkness, but is awakened by a bright light, as Udarnik's city lights up, possibly for the last time: the robot plugged his city into Tony and burned the phlogistone out of him by using it to briefly power his city. He's still mad, but maybe someday. Hasn't happened yet!

Also this issue: Tony's cousin Arno talks some of the bad guys/opportunists from the storyline, into working with him and Tony on the Stark orbital platform. One of them mentions Extremis to Arno, since that would've fixed his assorted ailments if Tony hadn't destroyed it; which is probably to underline Arno's eventual heel-turn. And Pepper has a new guy: public relations philosopher Marc Kumar. It seems pretty serious and he'll be thrown under the bus the second a later writer wants to ship Tony and Pepper like the MCU. (Nope, he went bad well before that!) Also, years back I did a few strips with that gold-and-black suit, but this might be the first comic I've read with it!