You're not a bully for not liking her. You're not a bully for expressing that dislike, or even criticizing her tracing. I am not defending the selling of traced, uncredited art.
However, when people get together to make fun of her and use their popularity to cancel her, or post videos like this well after the fact while while making money from those videos, then yes, that is bullying and just as, if not more despicable than the original offense. They're profiting off her suffering and indirectly the suffering of their fellow artists, since they weren't the victims. If it's wrong to make money off the pain of an artist like Nads6969 did, then it's wrong for them to do the same, especially when they're claiming to be a voice for all the people she stole from.
This isn't just hypocritical. It's childish and damaging.
Also, there's something called disproportionate retribution. Getting Nads6969 kicked of DA is bad enough, but understandable. But attacking her personally for her age, her motherhood status, and going to her private Pinterest to make fun of her is beyond the pale. She's gone. Why would anyone make sure she and the works she made -- and as much they are ripoffs, they are still *in part* her work -- is banished forever or perhaps bullied to suicide? You mention having internet fights are not more valuable than raising a kid, but there are only Internet fights because people are having them with her. There comes a point where it's better to leave her be. She's harmless.
Worst yet is criticizing her for blocking people she sees as harassers. If you can block you don't like, so can she. There's no difference. Allowing certain people to curtail an audience and depriving other people from that same choice is actively harmful. If it's wrong for her to dismiss a viewpoint of someone who hates her, it's for anyone to do that.
It's not right to pick on anyone like this over Internet foolishness, especially the Sailor Moon community. Instead of using this as an opportunity to actually practice the love and forgiveness this franchise is known for, instead, fans just decide to make people non-persons. I don't care if the target is a powerful e-celebrity like Doug Walker or a nobody. I can't take glee in the downfall of someone who is essentially no longer able to create. It would have been better to leave her alone but spread the word of what she did (and explain why it was wrong) instead of trying to take her down and make her into some sort of bogeyman when now she can't even defend herself.
Nobody is an "acceptable target."