Nah theres's a difference. It's like with movie leakers not actually leaking images of photos -- see the Spider-Men leaked image and the one with Daredevil that came out months ago. There's an understanding of what is off limits, and what is not.
Or to borrow a manga trope, they can overlook a certain amount. After all, spoilers could be lucky guesses. RAWS stolen from a shop? Fair dos. RAWs from the mangaplus process itself? Heck, this could even fuck over mangaplus as a service. Like, don't be sodding selfish. Blimey.