Also Swedes are an ethnicity: https://en.wikipedia.org/wiki/Swedes
Given the party's other points', I'd still say he's not talking about Swedes as an ethnicity but as a nationality, similar to how other non-far-right, conservative parties express their beliefs. I checked the page, and that quote is provided without the context, and since Sweden does not have birthright citizenship, I don't know if he's talking about non-naturalised kids or naturalised people.
Further complications come from the fact that stripping "bad" immigrants of nationality is now an acceptable talking point for liberal parties the world over, and that position is very popular with people of all origins, not just the ethnic Europeans. I'd even argue it's less popular among ethnic Europeans than those of other ethbic backgrounds.
But I'll acknowledge that defending that party's position requires giving tons of benefit of the doubt...
Don't put words in my mouth.
> No, a Somali who immigrated to Sweden is nationality wise Swedish and ethnicity wise Somali
You seem to misunderstand the concepts of nationality and ethnicity, and how naturalisation operates.
Please go ahead and define nationality and ethnicity. I’m happy to allow you to entirely define the terms to your ends and make an argument within those bounds. Please also tell us how the quoted statement calls out “naturalization” and “nationality” because it’s critical to you “not” doing racist apologia that both your definitions and the quoted statement are coherent.
If you ctrl f my username on this page, you'll find I'm arguing against racism and Islamophobia in another thread.
Let me make an assumption: you're an American liberal. Like many American liberals, you talk without knowing much about anything, with the purpose of feeling righteous, and appearing pure to others.
The world is more complex than what you read on the news.
I suggest you read "How immigration really works", by Hein De Haan, a book that explains why immigration is not a left or right issue. I also suggest you search definitions for these terms: nationality, ethnicity, naturalised immigrant.