I called it infamous not because I have a particular problem with it, but because of the way it's characterized by (Western, at least) fans. They snicker at and make jokes about the scenarios he apparently employs. (Admittedly, it doesn't sound like my thing, and I haven't looked too deeply into the material. It could very well be that I'm getting trolled.)
I agree that you can find genuinely disturbing things in the manga world and that Masamune's work is relatively benign (though some of his depictions of less-developed adult women might upset some). In general, I find the idea of commercialized erotica amusing, especially when coming from sources with more mainstream claims-to-fame. In these cases, I don't attach a connotation of moral bankruptcy or anything like that to the idea of them being "infamous", though maybe that's just me using the word wrong. I intend it more in the sense of, "Hahah, oh wow, THAT guy did THAT? That's crazy." Kind of like when we found out about Tezuka's softcore furry/snakewomen doodles.