Ralph confirmed on the stream that it was two black men. On a related note, I have to say that Bibble is an incredibly good sport when it comes to the Killstream's race banter. To be fair to Ralph, he does know how to talk to black people without it being pure cringe but the same cannot be said of at least some of the other people who have been involved in the production.
Ralph also gets animated about the Yemeni store owners who don't give a shit about him having just been mugged despite the thousand times he has been to their store before. Believable premise and if he's faking it, he acted it very well. By the way, if anyone still needed a reason to not support a certain type of convenience/fast-food store, then I don't know what to say to you.
Another solid hypothesis but to be fair to Ralph again, if we accept his timeline and impose stumbling-drunk-at-the-time-of-robbery upon it, then the man has impressive recovery skills.