I, personally, don't really have expectations for what human-earth accent space aliens should have. Is this just a personal thing about the specific accent they picked, because like I said earlier there are several 'Earth' accents used for aliens in this game already.
Now, I thought about this from another perspective to try and understand the backlash and thought "Well, how would I feel if he had a different very distinct 'Earth' accent like... Scottish?" And honestly, so long as they kept specific stereotypical scottish phrases out of the dialogue, it wouldn't bother me.