The number of people in my town that think our language is American, Mexicans speak Mexican, all Asian people are Chinese, and any random combination of cities/countries are part of the United States makes this very plausible.
Like you could say American is a sub dialect of English with it further broken down into accents. But I doubt most folks think of it that way, especially folks who say "I speak American" outside of an argument with the English.
Democrats are much more likely to have a Spanish speaker on staff at all levels. They are a more diverse bunch. Republicans, many from southern states will speak some Spanish, more so than northern white democrats. But, they are more likely to he a white only staff at each level, so nobody would pick up on it.
This is part of the reason diversity is important. It will be self evident to some people that things are not right, whereas those in a different world won't even notice.
I am probably completely wrong, but I thought he was saying that he could see the Democrats putting this exact sign up, not one like it. On the surface it might appear to be pro Republican, but in reality it is not. Just like the robo calls people were getting where they claimed to be Biden and told people not to vote in primary.
How the hell can you see this being put up by Democrats? What idiot messaging do they have that even comes close to the torrent of ignorant bullshit the republiQans swim in every moment of the day?