We don't have to get into a debate about PHP (I don't use it either); its virtue in this scenario is that after this guy gives up on the client, someone else can easily step in and pick up the project, because everybody knows PHP.
I think the degree to which this works depends on the sophistication of the code. If it's a simple form handler, then sure, it's an advantage to be using a language that millions of people know. If it's more sophisticated, it may actually be a disadvantage; the non-technical client has to sort through hundreds of responses to a job posting with no useful means of telling applicants apart. A language like haXe currently only attracts those who are genuinely interested in better languages. Such people tend to be decent programmers, so any of the 5 or so people who respond is likely to be a good choice.
