Don't you wonder why he was surprised?
He was surprised because he assumed our Conservative Party would be unhappy to have a PM with an Indian background. He assumed a major political party in the UK is racist.
It's his assumption that's shocking.
We have had queens throughout our history. No problem with it. We broke through the glass ceiling for women PMs in 1979. We now have an Indian PM. And it seems fairly unremarkable, because it didn't seem to anyone that it would be a problem. Instead, just like when Meghan Markle came to England and one of our princes fell in love with her, no one was anything but happy about it (regardless of her ludicrous victim claims).
It always amazes me how American Dem pols assume the worst about England's Conservative Party. But they are pro-science, pro-choice, pro-government healthcare, pro-green energy, pro- sustainable immigration, racially inclusive, anti-glass ceiling, and they share the burden of defence in NATO with the US, (unlike Ireland and Germany, say, who always get treated as heroes by the Democratic leadership, but they are defence freeloaders all the same).