The chap in the post isn't seeking highly available tech support. And it's not a free service - he paid.
Customers/users should never be left guessing about whether they've been forgotten or not. If you have users, have some flow like this:
1) Receive the customer communication. If you can't fix it immediately, then you immediately respond to the customer to tell them what you're doing, and clearly indicate when they will receive their next communication from you. It might be "we can't even look at this for six weeks", but if you've taken their money you should give it back.
2) Set a calendar event for your team so that they know about this if you get hit by a bus.
3) On the date, you contact the customer. If you haven't fixed the issue, then you indicate what you're doing at the moment, and give a new date by which the customer will hear from you.
If the customer is unlikely to be happy with the resolution then you describe why and describe their options.
Customers/users should never be left guessing about whether they've been forgotten or not. If you have users, have some flow like this:
1) Receive the customer communication. If you can't fix it immediately, then you immediately respond to the customer to tell them what you're doing, and clearly indicate when they will receive their next communication from you. It might be "we can't even look at this for six weeks", but if you've taken their money you should give it back.
2) Set a calendar event for your team so that they know about this if you get hit by a bus.
3) On the date, you contact the customer. If you haven't fixed the issue, then you indicate what you're doing at the moment, and give a new date by which the customer will hear from you.
If the customer is unlikely to be happy with the resolution then you describe why and describe their options.