So many levels of fail
End-user - while it is understandable that he was upset when he thought he had lost all of his email, he did himself no favour in blasting the IT department. All he accomplished was to alienate them so bad that no one wanted to help him. If you need something from someone always make them WANT to assist you.
IT Dept - while no one enjoys dealing with a verbally abusive customer, they really messed up when they put off helping him until the other tech returned from vacation. Instead of a quick investigation and providing great relief to the user they contributed to an environment where the user was left to get angrier and I'm sure this generated a lot of talk about lack of support from IT. Even with it being user-error and a good outcome, complaints about poor support would have been valid.
Techie - he did everything right before going on vacation, and patiently allowed the user to vent a bit while explaining the issue, AND quickly resolved the problem. All aces until he had to go and get his dig in. So much potential to help undo some damage but his need for revenge for the rant lost him his high ground.