How much can you tell about a man from reading two of his books? I don't know, but I feel that I have at least some idea of the general intentions and point of view of Spong. To a large extent, I can sympathise with him. Spong seems to be someone who has identified issues or difficulties to be worked through, and is struggling with what to do about them. I can certainly identify with that. In spades. But his ideas about how to deal with those issues seem radically different than my ideas. I will freely criticize Orthodox beliefs, that's true (though usually I try to use some humor, so people know that I do not mean to be malicious), yet I have a basic respect for orthodox Christianity, and wouldn't presume to change my role from critiquer to reformer. Not when it comes to basic doctrine, anyway. But Bp. Spong, he has gone well beyond critiques, and even beyond calling for reforms. He wants to completely recast Christianity using his own theological mold.
As to his relevance in this discussion, I don't know what consequences Spong has experienced for his, shall we say, maverick positions. It seems that he is still writing books. And I expect he is still free to say whatever he wishes--perhaps even more free now that he is retired. On the other hand, what do you think would happen to an Orthodox bishop if (for example) he wrote a book denying the literal resurrection of Christ? Do you think he would remain a bishop in good standing, and be allowed to write a book every couple years calling for a new Christianity?