I mean it's a bust even if fake that have nipples, good enough reason to censor. Plus it came censored in the raw anyways so lol (idk if it's censored on physical volumes).
Oh I do notice now that the censorship is a bit over the top with the cleavage part too lol
Since this is manga, all busts are fake. Only in photos they wouldn't be. In that sense, it makes sense the mangaka censors both. That being said, I never took this as a fanservice manga (nor some super serious crime manga), so censoring was more or less to be assumed. However, it's just beyond brutal and primitive here, which ends up ruining the art of the affected pages. It would have still been funny if the author has just used the excessive black boxes on the first relevant pages (when the thing was lying on the floor), but then just drawn the rest so that there would be no reason to apply that censorship as precise as a shotgun.
Who knows why any author would want to do this to their own art.