What does “such occupation” imply? Doom is normally the principle antagonist for Marvel.
One other factor is that evidently it was by no means filmed correctly (in films), so sure, there’s a cause for concern, however this has nothing to do with the casting, however on the a part of the writers / and so forth.
Though will probably be unusual to see Downey within the function of one other character in the identical universe, after this time he performed the gentleman with an iron fist.