The fearful comments are not from Apple developers, but from freetards who have hated apple for the past 20 years and been making the same kinds of comments for that same period.
Meanwhile, those of us who have been developers for apple platforms during that time have never seen apple screw us over and find this kind of fear to be asinine.
It makes for good press to boost your page views, though, and so any burp eminating from cupertino is used to rationalize wild speculation and assertiosn that it is proof that steve jobs is a control freak who wants to run your life.
Apple introduced App signing in Leopard. You've been able to produce signed apps since around that time. That's all the appstore on the mac needs. Apple won't care what toolchain you use...