That by saying, "From Latinos," they were only talking about the individuals who wrote the letter, who are Latinos.
Therefore, by YOUR LOGIC, you can use general terms to talk about specific people.

So, the Latinos I know that hate blacks, as Latinos, profess this, so I can say that Latinos hate blacks. "You're supposed to distinguish between their use of a plural designating a community - African-Americans - and the use of a plural meaning 'a number of Latinos'."

--