It's not the same as not wanting your picture taken on a demonstration, it's the same as not wearing a tshirt for the next year that says "I was on this demonstration".

Doing a blackout for twelve hours harms your business, fucking up your SEO harms it again. Obviously in this, as in any protest, there is a decision to be made on what to do. Why not only blackout for one hour? Why not blackout for an entire month?