The great beauty of mathematics is its lack of subjectivity. Follow the rules and you get the correct answer. I am truly blessed, I love being a mathematician. Linear algebra can be taught in many different ways, if you are into differential geometry then you will teach it in a different manner than someone who likes abstract algebra. Both subject-centric teaching methods are just as valid. Race has no place in mathematics.
Not a mathematician here but a heavy background in it (PhD Engineering & Applied Physics). Wholeheartedly agree with you, the sad thing is this kind of stuff makes racists look correct.
Common sense, if it existed in this P/C world, would prove you right ... but not in the world we live in today.