I'm not sure BLM support is "mainstream". Home Depot hasn't said anything official about BLM to my knowledge, and you hear loud pro BLM people saying they should be boycotted [1], but I think they're doing fine. Their stock price is as good as its ever been.
I think what we're seeing is a case of "minority rule" [2].
I think my point is more that people who actually change their behavior based on whether or not a company explicitly supports BLM is not a majority. It is probably a small minority. If that 57% actually boycotted businesses not supporting BLM, Home Depot would change their tune quickly.
Interesting.