Don't see an issue at all. Some people are way too sensitive. This is a heartless action flick, remember. If it even aspired to be more than that then maybe there could be cause for concern.
As it stands, they're two retards. Would we be having this conversation if two black characters had actually played the role in a similar flick? Just b/c they're robots people are trying to impute way too much into them and who they're supposed to represent.