That seems to be a US rule [1], not a condition imposed by the knighting jurisdiction. Maybe some other countries have similar no-titles rules, but I couldn't

That seems to be a US rule [1], not a condition imposed by the knighting jurisdiction. Maybe some other countries have similar no-titles rules, but I couldn't find any (might be searching for the wrong terms). [1] https://en.wikipedia.org/wiki/Foreign_Emoluments_Clause https://en.wikipedia.org/wiki/Foreign_Emoluments_Clause