2 issues
1) Managing client expectations
Managing client expectations is one of critical aspects of providing a Client facing service and successful client management is an ongoing task
No doubt some clients have unrealistic expectations and sometimes they are impossible, but it is the Provider's job to align the clients expectation with the ability of the Provider to deliver.
Not responding to multiple calls and emails makes that job very hard because it does not cultivate trust or peace of mind.
I think MR's post was trying to realign the client's expectations to the realities of a Sole Trader business. I do empathise that customers don't have any insight into that. I am also not a TA, but am in a customer facing service industry, and I can say that his post is definitely the wrong way of going about it.
2) The Skill of Delegating
I suspect MR's business model needs to be re-imagined. I don't know enough of MR's office practice to advise directly but there are lots of things that can be done.
One of the most important skills that a lot of Sole Traders have difficulty with, is the ability to Delegate.
We all think that no one else can do a better job, but that is a fallacy.
We then overestimate our abilities, and fail to recognise that others can possess the required capabilities or be trained in it. I think it is called the Dunning-Kruger effect.
Inability to delegate imposes huge costs.
In a sole trader scenario, it bakes in a single point of failure - no one to solve an otherwise simple issue. That is clearly seen here by everyone, where the client is worried that something happened to MR and there is no solution even with the ticket issuer.
The other cost is personal fatigue and mental exhaustion - as alluded to by MR
Cognitive bandwith is limited and the business is at risk of becoming error prone.
The solution is to actually start delegating - despite MR asserting that he can't find anyone like him, it is actually not necessary to find a MR clone. Even someone, who is 20-50% of what MR can do, can be immensely helpful . Start slow, hand off small tasks, then increase as the case might be. Who knows, a good assistant can sometimes transform the office because they can provide a different perspective.