Appreciate the well written response.

I disagree though. Sure, racism is just a word we made up, as are all words, but words must have fixed a fixed meaning or else they stop making sense or end up inaccurate. For racism, at least according to Miriam-Webster which I hope we can agree is a serious source, the word is defined as to discriminate, oppress, hold prejudice or produce a superior trait in a certain race. Rough snippet as I am on mobile, but feel free to read the definition in more detail.

Nobody with the ability to digest lactose feel superior to those who cannot. Nobody is discriminated against because they cannot digest it.
Nobody really cares.

And because it is in no way bound to a particular race only, it just cannot be racism. Using that word here waters out the definition of it.

I am probably beating a dead horse here, but it has been bothering me for a while that the bar to throw this word at someone is not just low; it's completely gone, and that is indicative of a serious problem.
Calling someone a racist is supposed to be a serious accusation.

I'm just a random guy arguing with a stranger online. It's a waste of both my time and his as neither of us will change our minds. I just needed to vent a little and speak up against those who, in my humble opinion, willfully and maliciously sour the debate climate. It's beyond rude to call someone that without it being true.

Thanks for reading and have a great day.