Will you be posting those 750-word first pages that you request? If yes, does this mean that anything printed is Used Goods and I would be essentially throwing X years of work into the streets of the meat market? (Think between Hudson Street and the river, LES, ms pages fluttering down like pigeons among the ratcrap and pig guts in the pavers.)
You aren't under a blood oath to send pages. You can decline.
However..having your work posted on this blog in no way limits your publication options.
It's posted on a blog. Any nitwit who considers that "published" is someone you'd want to avoid working with anyway.