By the same argument we should criticize and negatively judge the American Revolution as well.
This path of argument seems unable to acknowledge that there are times where "the law" is so unjust that you are left with no non-violent actions whatsoever. I think it's fine if you believe this, but you should be able to clearly say that you believe in nonviolence in all situations and that any deviation from that path is immoral.
The laws Mandela broke were not the same ones he thought were unjust, at least, it seems he broke a superset of the laws he thought were unjust. He did this as a means to an end.
I'd like to say I believe in non-violence, but it's one thing to say it, it's another thing not to punch you after you've just pushed my wife.
This path of argument seems unable to acknowledge that there are times where "the law" is so unjust that you are left with no non-violent actions whatsoever. I think it's fine if you believe this, but you should be able to clearly say that you believe in nonviolence in all situations and that any deviation from that path is immoral.