I am not updated with this but as far as I know, Korea has a lot of restrictions on cryptocurrency, therefore, it might be true. You can create support ticket and be sure what is the truth. Don't put any of your token/coin before being sured. Otherwise, you will lose all the money.
I am always vigilant, I don't want to lose my tokens, because here I just want to find the right information.
I think if you lived in Korea, Indonesian, Singapore, you could use upbit.com because I found something on the website.
Here you go:
And then, this is what I found in the FAQ in Account section:
Btw, do you want to tell what tokens you want to sell in that exchange? Because you might find another exchange for the tokens, so you don't have to register in upbit.com. Maybe idex.market, etherdelta, etherdelta was a popular exchange for selling the tokens ERC20 and I see that there are many tokens inside those exchanges.