Originally Posted by The Overlord
I think Thor works best fighting gods and monsters from Norse mythology. That's part of the reason why Mr. Hyde started off fighting Thor, but ended up as a Daredevil and Captain America villain. Radioactive Man is more of a science based villain and being a Chinese scientist fits with the plot of IM3 that is set in China. That's why Radioactive Man is in this movie and why Thor will be fighting Dark Elves in his next film. How would fit Radioactive Man into a Thor movie, he wouldn't fit in with the magical enemies Thor usually fights and wouldn't be able to carry a movie by himself. Thor works best in a fantasy setting, so having a sci fi character would be out of place.
This. Thor basically has two complete rogues galleries. An Earth one with Absorbing Man, Radioactive Man, Mister Hyde, Grey Gargoyle, Cobra and the Wrecking Crew, and an Asgardian one with Loki, Enchantress, Hela, Surtur, Karnilla etc.
Heroes have been borrowing his Earth based Rogues since the 1960s and 1970s. It's nothing new. Radioactive Man has also been associated with the Mandarin, The Crimson Dynamo and Titanium Man in the comics, so to say he's not an Iron Man rogue is wrong. He's one of those characters who falls into two rogues galleries, the way that Kingpin is both a Spider-Man and a Daredevil villain, or M.O.D.O.K. originated as a Captain America villain, but wound up fighting Hulk, Iron Man and Ms. Marvel.