So I decided to let WPExplorer know, and tweeted @WPExplorer. Soon after, I discovered, that WPExplorer is actually following me, so I deleted the tweet and sent a DM on Twitter instead.
The next day, suddenly @WPMUdev on Twitter wakes up and starts asking me to provide the link of the article to "further investigate the accusation". To which I politely declined a couple of times. At the time I didn't realize that the link has been long cached in archive.org and I wanted to give WPExplorer time to decide on his own what to do about that before WPMU "inspects" the issue.
I'm very disappointed seeing such behavior from a huge site like WPMUdev. I was under the assumption that copy pasting articles was what low level "SEO hacking" sites do, not the "big guys".
Isn't this shameful amongst blogs and websites ? Is it okay to publish "inspired" ( or copied ) content without mentioning the original author ?
As @TimothyBowers said, I could have emailed them directly, but instead I started a public conversation ( https://twitter.com/TimothyKBowers/status/666362562666172417 ). Because of it I guess I am obligated to provide WPMUdev with all the details that they require or they won't leave me be on Twitter. Well - You wanted it public, you got it.
Twitter conversation: https://twitter.com/justnorris/status/666363207557189632 Link to the article: https://web.archive.org/web/20150421051207/https://premium.wpmudev.org/blog/10-drag-and-drop-page-builders-wordpress/
p.s. I am by no means a writer, so excuse my writing style and form. Thank you for reading through my public rant :)