There isn't to say some issues can't occur outside of the program but people are taking this way too seriously. For one thing, the so called "changes" for LINE's policy involving sexual material is no different than any other site, including Tapas. I'd kind of assume this isn't even new for LINE.
But as for Adsense, they don't care what your mature content is, they care in how it is presented. You panel of a guy smoking cocaine doesn't bother them. Your guy actively showing the positives of cocaine and the story treating it is an explicit positive, does bother them.
All of the policies are not meant to deny every single mature content around. It focus on the intention of of the work, especially when it goes outside of fiction and dwells into actual reality. More importantly when it tries to express what would be wrong as fundamentally right.
LINE would literally have to pull 90% of its content and all of its featured series if it couldn't promote one single bit of a mature content. Some uncertain issues may occur that hopefully LINE and/or Google will deal with.
But you people make it sound like LINE and Google is going to demonetize every remotely mature series, sneak into your house and slit your families throat. Then you're going to log into LINE or something and see nothing but kittens and puppies in Discover and Featured. Meanwhile you're wondering where your favorite series and author is.
But unfortunately, LINE had to kill them for besmirching their precious and pure website.