There are really 7nm chips that are designed using a different approach, but have similar characteristics. It's kind amusing how people think that there's something magical involved in making these types of chips that would prevent China from making them.
I think hes not questioning it because china, but because nm between different fabs isnt comparible. E.g. finfet nm isnt the true nm used by older definitions of what nm means, which is why intel for instance, changed their naming on its fab process to match the rest of the industry. (E.g "Intel 7" is actually a well processed 10nm traditional definition chip that has that name because its conparible to TSMC 7nm)
TSMC N7, N7P and Intel 7 don't use EUV. It's all quad patterned DUV. DUV lithography has been in use since the 1990s going from 800nm to N7P.
Every single node after TSMC's so called 16nm has been all marketing. It would've more accurate to call TSMC 16FF as 20nm FinFET. This is why Intel brands what they themselves called 10nm as Intel 7 to bring their marketing more in line with TSMC's.
SMIC N+1 has a density of 89 million of transistors per mm² while TSMC N7 has 91.2. TSMC 10FF and Samsung 10LPP only offer slightly more than half that density.
I literally linked an article explaining that China uses an alternative approach with chiplets. Maybe go read it. Also, it's not like China can't develop DUV themselves, or just hire people who already developed it to build it for them. There is no magic here.
I guess we'll find out who actually understands modern chip manufacturing when these phones come out won't we mr. modern chip manufacturing understander.