I interpret "undisclosed family reasons" as being "to preserve his health, sanity and marriage".
If it is correct that he is being paid only £200,000 p.a. for what is probably the trickiest job since Richard Granger tried to put the non-existant planning into Tony Blair's National "Plan" for IT, then no wonder he was open to persuasion to go home before he suffered the fate of Philip Langdale.
I have met individuals capable of doing the job he was being asked to do, but they have been senior civil servants (or local government officials) coming towards the end of their careers, capable of politely facing down permanent secretaries (not "just" ministers) without causing offence, because they are no longer seen as a rival but as a former colleague trying to find a win-win solution for all, not just their own department.
This is a job for a consummate seducer, not a ball-breaker.
P.S. Just read the excellent piece by Mark Ballard on why "Agile" methodology and DWP was a marriage made in hell. It may also explain Pitchford's departure - especially if his final months are to be spent organising the divorce: although whether it is to be a divorce between DWP and its current contractors remains to be seen. Parts of CapGemini, HP and IBM have been responsible for some very impressive examples of the use of "agile" in the public sector to deliver major systems at a fraction of the cost and time anticipated. One such is the on-line renewal routines for driving licenses - where story of how the system came about is taboo.