While I'm aware some campaigners use a narrower meaning of #racism that isn't the common usage one.
So when you claims you can't be racist against whites (in the sense of personal prejudice isn't racism), what average people hear is you believe ethnic minorities are allowed to spread lies about white people.
Not mentioning this because people who use the narrower sense are wrong; just highlighting why middle segment of society we want to win might not hear the message.