Why would he? His mental problems were well documented and part of his medical special approval. The real problems only started after he was already on the job and didn't disclose the resurfacing problems, as he should have done. Any pre-employment letter from his GP wouldn't have prevented anything.
And of course he passed (twice) a rather comprehensive psychological screening during his cadet selection and after he came back from his time out to deal with his depression. Didn't help at all, and it isn't designed to do it anyway, it is just there to see if he conforms to a certain psychological profile and fits into the pilo team of Lufty.