Yep. While maybe it's "not cool," (I guess, depending on how much work Delve did in their fork, in which case it could be "totally cool"), there is no legal problem with doing this and if someone is "blowing the whistle" about this, they don't really understand open source.
You clearly did not read the article. Why post something so confidently when you're not even informed on the topic?
> A permissive license whose main conditions require preservation of copyright and license notices.
How is there no legal problem with violating the license terms, which explicitly require attribution?