Do you remember how sometimes Batman will say that he's not a part of the Justice League, even though technically he is one of its founders and arguably the one who funds the entire operation? Well, it's possible that this might be the case with the Tony Stark of Earth-838, which is the alternate universe featured in Doctor Strange in the Multiverse of Madness where the Earth is under the protection of the Illuminati - not the Avengers.
Speculation about where Earth-838's Tony Stark was in the Doctor Strange sequel aside, there are rumors suggesting that he's out for blood after what happened to his universe's team of superheroes.
claims that a previously unseen Iron Man from Earth-838 will appear in the MCU and Robert Downey Jr. could return to play the said variant. This would be in line with the earlier rumors that RDJ