No, Blizzard leaving a benign symbol in the game is saying “we don’t recognize you, your evil ideology, nor your attempt to use this symbol in a way for which it was neither created nor intended.”
That knot - unlike the swastika flag - was not created for the purpose of racism, and its existence in the game was based on a benign interpretation and cultural connection to a character.
If American racists came up with a stylized noose flag representing their cause, then by all means ban that flag because it has no other possible meaning. Anything beyond that legitimizes 150 years of misuse by a fringe group in the US over the thousands of years of use by dozens of cultures as a symbol for something else, and over the purpose for which it was included in the game.
By giving them the power to get symbols that aren’t theirs censored by misusing them, you’re showing them that they’re living rent-free in your head, affecting your perception of those symbols and slowly changing it to match theirs. They may not be “welcome,” but they’re effective and you’re letting them know it. Don’t give them that power by just not giving their ideology the time of day; that’s how you combat racism effectively.