^^ we have lolicon on Flandre and Suwako and they're both well over 100 years old. I'd say from the looks of it Tewi could totally warrant the tag in this pic.
I'm not a big ReiMari fan, but I gotta say that I still prefer them older when they do... stuff... like this. As is the case for most characters, really... but, what can ya do, it seems like this dude likes ecchi lolis (what a waste of his decent drawing skills).
I'm not that good at Japanese, but from what I can gather from the Twitter, it seems that the artist was trying to portray an unhealthy, codependent relationship.