I was also pleasantly surprised by the good service from 9mbi. Having made a purchase unaware of the 'buy one get one free' offer, I received an email asking me what I wanted, and a link to download my selected product shortly afterwards. This was a few months ago.

I would suspect foul play only as the last possibility -- he would be shooting himself in the foot to deliberately mess with the terms of his RMP offer.

But whatever the reason, the OP's message is still valid... whilst we may hope on a personal level that he's okay, if he's not responding to emails it's probably best to avoid purchasing from him for the time being.

"If I were a shadow, I know I wouldn't like to be half of what I should be."
Mr Otsuka, the old black tomcat in Kafka on the Shore (Haruki Murakami)