I don't use FB, but I guess this is about blocking in general. I don't think it's either right or wrong, and it's more about what we can take and what/who we want to be dealing with.
There's a reason I personally don't like blocking people, unless it's some weird "harassment" that just won't stop, or if there is no other way to stop the spamming of pictures and details I don't care about in the least. I'm already restricted in my connections with others, I don't go out nearly enough, I don't actually deal with people much as it is. If someone doesn't agree with me or even challenges me, I can practice my tolerance for people being different and even aggressive, and just let it be, instead of letting the situation have power over me. I can have my bad days too, and if I'm dealing with someone then, I do wish that they would just let it go and not let it bother them.
I am extremely reactive by nature and somewhat judgemental too, and I don't want that to be the case. This doesn't mean I should stick my head into whatever it is I don't like, but at least I can learn to be a bit more tolerant, and remind myself that I shouldn't always give in to my knee-jerk reaction, as if I had to fight or flee, or to do something right away. Some things I can just let be, accept them even if my emotions tell me otherwise, and move on without forcing myself to respond to everything. Because if I reacted every time with action when I'm dealing with someone saying something I really don't like, I would find myself eventually from some small hugbox or echo chamber where differences or weaknesses aren't tolerated, and I would find it really hard to deal with different people then. Not saying this is the case for you, but it is for me. Anyway, I don't think it's such a big deal, I just felt like typing this wall of drivel.