Sorry, but you couldn't be 180 degrees more wrong on this one. Unprofessional is failing to meet deadlines and then failing to have good communication about it with the customer. Unprofessional is ignoring and avoiding many different forms of contact attempts from said customer and absolutely refusing to communicate with them.
I didn't see anything the least bit unprofessional about the OP's post. He [presumably] factually stated a situation at hand, without trying to be dramatic about it, and asked if anyone knew of any reason why Mike wouldn't be able to communicate with him, and if not if there was a better way to contact him other than the three methods he had already tried.
I will ask you again, and please answer. If the OP has mailed letters, emailed, and called by phone repeatedly over time, and Mike refuses to respond, if posting on AzB asking isn't the correct course of action in your opinion then what do you think the correct course of action is? Just wait around for years to see if Mike will ever contact him, and if Mike never contacts the OP before he dies decades later then oh well? What should the OP do when Mike refuses to communicate with him, and how long should he wait before he does it?
To me and other posters this sounds like a classic case where your bias of knowing and liking Mike is not allowing you to see the reality of his actions. And for your information having 8 posts is absolutely immaterial to anything here.