From elsewhere in Tolkien's letters:
"I do think of the 'Dwarves' like Jews: at once native and alien in their habitations, speaking the languages of the country, but with an accent due to their own private tongue."
Tolkien's obsession was language.
But again: the big stereotypical profession of the Jews was moneylending. The Dwarves don't lend money: they mine and make stuff (and eat pork). At best, your argument boils down to "well, Tolkien said the Dwarves are like the Jews, so that's evil stereotyping!"
Depends on the country. Tolkien just got annoyed that his interest in Germanic languages and Norse mythology got hijacked by the far-right (he famously called Hitler a 'ruddy little ignoramus' in one of his letters).