That actually makes it worse - it panders in the worst way as it plays on the ignorance of the audience about his actual heritage. Not sure how a white British citizen moving to another British colony legally and working his way up in the system solely due to his effort and abilities is an "allegory" of anything in current events. In fact, it is most likely the exact opposite of the reason the audience cheers if they thought about it for a second instead of reacting like seals clapping being triggered by the word "immigrant".
Eh... he was an immigrant though by definition. The very first line says he was the son of a Scotsman so it’s not like they aren’t mentioning that.