Does not sound "personal" to me at all
I'll admit that I have not studied the details of the case. But it does sound to me that the junior staff involved were acting in a professional capacity, on behalf of their employer, in this case a public authority, though it might have been a private business under different circumstances.
I expect a person I am dealing with to introduce himself/herself, which is just common politeness. I expect to be able to refer to him/her by name if the issue I am trying to resolve is referred to another person. I expect to get enough information to understand the area and the extent of the person's competence and/or authority. I expect any written communication to be signed with the name and the title of whoever wrote it. I do not need personal details such as the person's home address, FB login, or personal mobile number. I deal with him/her as a representative of the organization. Oh, and by the way, if he/she is, say, rude to me or otherwise behaves less than professionally, I expect to be able to complain against him/her personally. Though an actual person is involved the context is not personal at all.
Is it possible for a disgruntled customer to Google Sigourney (or hire a PI, for that matter), find out all sorts of personal info, and, if the customer is crazy enough, do something nasty to her personally if he thinks that she is to blame for delay/denial/whatever? I suppose it is. Is this potential hazard serious enough to scrap all the norms of human and business communications? I would hope not.
It is not clear why the gentleman with a very unusual name had to resort to FOI to get the names of the people who handled his case at FSA in the first place. Had he just forgotten to write them down or does it say something about FSA's practices?