Strong start, but fades toward the end

Philip gets some divine guidance to the Ethiopian eunuch. He walks (runs) alongside him, helps him understand scripture and answers the question, "Look, here's water. Why shouldn't I be baptized?"

That's where Philip's strong performance fades (Pun!).

He disappears. Poof. Abracadabra. Gone.

Now the Ethiopian was ecstatic. He was feelin' it. For the moment. After we just read the story of the relapsed Sorcerer we find Philip ditching his new recruit. Are we supposed to assume that because this eunuch was a devout Jew (He was studying scripture in a moving chariot on his way back from worshipping in Jerusalem, after all. [Would that be the ancient equivalent of bible blogging at Starbucks?]) he would step right into being a devout disciple? If so, he was one of a select few.

I think this is one where Philip drops the ball. If Paul Harvey were still around, I'd love to hear "the rest of the story" and find out what happened with this Ethiopian out there all alone.