Be interesting to see the true version of events.
Not saying yours are not correct, just you mention that is the context you heard.
I think as soon as you tell somebody to “go back to where you come from” (I imagine it would’ve been a bit more expletive ridden.) you’re on some pretty slippery ice, unless your telling him to to not mark you so closely.
I agree, there are worse things, but it definitely has racial undertones in how I imagine the conversation would have gone.
No issue with red card in this circumstance. 6 week suspension for a 18year old seems a bit much, maybe miss a week, give him 12 weeks next time he does it.