Lots of women use "boku" these days, and you see lots of female futa using that pronoun too. Just do a web search online if you don't have the personal experience of this, but it's definitely a real thing.
In any case, e-hentai tagging never was determined by text references alone, but by what a character actually appears to be.
This entire "hengen monogatari" group is a fucking shame. They take Sano Toshihide's original work (he had no say in any of this), make shitty edits to it, and then resell this absolute garbage to gullible or uncaring morons. Nobody should buy or share this stuff around. Instead, be sure to spread the word so this stuff never sells again and if you somehow know how to get into contact with Sano Toshihide, bring this to light with him.
I know this comment is over a year too late, but the reason you see works based Sano's art is because, in fact, he does sell these images for use.
G.J sells a "eroge maker" kit (http://www.teck.co.jp/gj/products/sano/index.html) that's been on sale since 2009 and gets updated occasionally with images from their newer games. The kit comes with a simple eroge engine, some simple tools, as well as the images in a separate folder.
The main things license agreement doesn't allow is the use of their music (sound effects are ok), as well as just packaging all the images unedited and selling it (basically reselling the kit). Apart from that the whole point of the kit is to allow people to make their own eroge/H-manga/CG/whatever that don't have their own artist or can't afford to commission one.