Apart from the despicable thing (IMHO) of being an absent father, I wonder how his mental health will be once he is done. As an avid trekker myself (I did the a good 60% of E1 trail [1], Camino the santiago, Via Francigena, and others) every time I was away for a prolonged time (say longer than 2 months) coming back to normal life was really hard. I believe they now call it post-trail depression.

[1] https://e1.hiking-europe.eu/en