And I quote "This, of course, willfully ignores the simple fact that not only so much more goes into sexualization than nudity (like framing, posing, expressions etc.)"
And yet they themselves don't seem to understand this. There are women who do indeed find Raiden and Conan sexy, and they don't need suggestive poses or lingerie thongs to do it. What women and men find sexy is not the same. Raiden wasn't put into his position to be sexy (at least I don't think so), but that doesn't make him less sexy than Quiet (he's still a pretty boy after all, and his good looks were intentional). You could even make the argument that Raiden's nakedness is cheeky snipe at fanservice in general.
The picture they use to illustrate their point actually further undermines their point; the woman on the right is only non-sexy because she was intentionally drawn to look ugly. If the woman on the right struck the same pose as the woman on the left and lacked the severed head , she would still be ugly, no matter what she was wearing or whether or not she had a head in her hand. If the woman on the left was drawn with a head in her hand and striking the same pose as the woman on the right with a scowl on her face, it would still be off-putting due to the violent nature of the picture itself, but the character would still be hot. Red Sonja is closer in personality to the woman on the right, but many still find her sexy. They are inadvertently admitting that they want to make females uglier to make them less sexualized.
Nudity isn't inherently sexual, but human beings, being sexual creatures, will sexualize another naked human being; its inherent to our DNA, and it generally takes a lot to dissuade us from doing that. Sexualization itself is in the eyes of the beholder; you could argue that both Quiet and Raiden were gratuitous and could of had their respective scenes removed, but what's the fun in that?