That’s hard to argue with.
That’s simplistic to the point of being racist. There was a majority in Wales for leaving, which can hardly have been English exceptionalism. The single ethnic group in these islands that was most strongly in favour of leaving was one of those in Northern Ireland, which would certainly not be considered English. And there was a non-trivial vote to leave in Scotland, which far exceeded any population there that might identify English.
Calling leave voters English exceptionalists is probably a bigger trivialising calumny than calling them thick racists.
Still fighting the wrong battle as well. The vote was whether to remain or leave. As with all separatist votes, the sole or primary objective of the separatist is to separate. You are wasting your time in arguing over percentages of GDP. You have to win the separatist/unionist argument. We lost, because we didn’t even fight it.