I think both instance admins have a valid stance on the matter. lemmynsfw appears to take reports very seriously and if necessary does age verification of questionable posts, something that likely takes a lot of time and effort. Blahaj Lemmy doesn't like the idea of a community that's dedicated to "adults that look or dress child-like". While I understand the immediate (and perhaps somewhat reactionary) concern that might raise, is this concern based in fact, or in emotion?
Personally I'm in the camp of "let consenting adults do adult things", whether that involves fetishes that are typically thought of as gross, dressing up in clothes or doing activities typically associated with younger ages, or simply having a body that appears underage to the average viewer. As the lemmynsfw admin mentioned, such persons have the right to lust and be lusted after, too. That's why, as a society, we decided to draw the line at 18 years old, right?
I believe the concern is not that such content is not supposed to exist or be shared, but rather that it's collected within a community. And I think the assumption here is that it makes it easy for "certain people" to find this content. But if it is in fact legal, and well moderated, then is there a problem? I don't believe there is evidence that seeing such content could change your sexual preferences. On the other hand, saying such communities should not exist could send the wrong message, along the lines of "this is weird and should not exist", which might be what was meant with "body shaming".
I'm trying to make sense of the situation here and possibly try to deescalate things, as I do believe lemmynsfw approach to moderation otherwise appears to be very much compatible with Blahaj Lemmy. Is there a potential future where this decision is reconsidered? Would there be some sort of middle-ground that admins from both instances could meet and come to an understanding?