I'm not 100% with you on this actually.
People get into hobbies for different reasons. Some people do cosplay to learn a skill, for love of the character, to have fun, or even just to enjoy being a model.
While it may not be your reason for cosplay, I think that any reason is as valid as another. It's almost like saying "oh you just got into star wars because the actor that plays new Spock is hot? You're not a REAL fan." I think it comes down to another form of 'fake geek girl' profiling.
As far as a cosplay themed sexy magazine, it's a business. If he can do it without getting sued for copyright infringement, whatever. Just because I have boobs doesn't mean I'm in playboy= Just because I cosplay doesn't mean I'm a stripper.
But also find it incredibly insulting if you start throwing around 'slut' so maybe try to actually respect people's decisions about their own bodies and not act like them making those decisions makes them less human. Sex workers are people using their personal assets to make money to survive on. If paying rent means striking a pose in an outfit they may or may not understand, I don't think it's anyone's right to judge them.
If someone wants to wear a sexy costume because they're comfortable in their own skin, you can back off and look at someone else's costume. Ignore them, seriously. If they're doing it for attention then it'll probably stop. If they're doing it because they want to and feel comfortable that way, then they don't need your approval anyway.
The same applies for men who wear shirtless or revealing costumes. I haven't seen them judged for it, but I'm sure someone has.
This whole thread reeks of slut shaming, I'm disappointed in this community. You'll all run screaming to the aid of someone getting called 'too fat' or 'too black' or 'too pale' but God forbid you defend the people who are 'too slutty' and actually also deserve not to be demonized and insulted.
Cosplays in Progress:
Haruno Sakura (Shippuden)
Theodora (Oz the Great and Powerful)
C. Viper (Street Fighter)
Twilight Princess/BRAWL Zelda (Green BRAWL ver)
Tharja (Fire Emblem Awakening)