Of course he can take a stance. And by the same token the rest of us are free to criticize it.
As they are free to criticize Spotify by putting their money where opinions are and taking their content elsewhere.
Free speech all the way around.
Within their legal rights? Sure. But they are advocating for others to be silenced in the same breath, not just silently pulling their content. In other words, they are using power (financial power, celebrity influence) to silence others. That is incompatible with the ideas underlying a classically liberal free society.
Sorry Neil Young isn't the all powerful boogeyman that you think he is. He isn't censoring joe rogan because he doesn't have that power.