Not at all saying that IP was pulled, but his existence due to being in Dark Reign is kind of an open secret so I don’t feel weird about answering this. Marvel’s only comment in that direction was to make sure that we had at least one pose showing Osborn’s face so that people didn’t get confused.
MPQ Newsletter
Which color tile is the most matched tile color in Marvel Puzzle Quest? Answer: Green is the most matched tile color and we imagine with St. Patrick’s Day coming up, that fact may stay true a little bit longer.
“Color tile” must not count TUs. The way the AI matches them they would have won by a landslide. 
Even the recent Iron Patriot comic book series feature James Rhodes as the Iron Patriot. I understand they are trying to match the movies, but usually they come up with some extremely convoluted and dumb storylines in order to justify it, for example, black Nick Fury and organic web-shooter Spider-Man.
However I think in MPQ they are probably holding off Iron Patriot’s launch for when he’s actually introduced into the game’s storyline, which could be a long while given that the Dark Reign story seems to have effectively been shelved.
I think if you’ve played this game for more than, say, a month, it’s 100% no surprise that green is the answer to that trivia question…
Which character is the most used character in Marvel Puzzle Quest?
Answer: Thor (Marvel NOW!) is the most used character in the game.