It’s a bit harsh saying all Commissioned RAF controllers are arrogant, I like to think that I have the best interests of those that work with me and those under my command. That said we do have some real ‘characters’ so to speak, usually at each extreme end of the spectrum, the quickly promoted Sqn Ldr who thinks he is an expert in your field and the old Flt Lt who blames everyone but himself for missing out on promotion (I’m the latter but without the blaming other people bit). I find it’s best to treat them with the contempt they deserve.
Onto the OP’s question in hand, I think it speaks volumes that you, as his friend, point out that he is too arrogant to consider an ATSA position; I wonder, have you given him some constructive advice in this regard? How is he pitching himself, has he been LEO, UTO, Safety Management in the past? If so he must civilianise that aspect of his CV. He needs to visit, see ATC Units in person, network etc, you can’t just send your CV to all and sundry without any other contact, he is up against people who may have been laying the groundwork for a year or more.
What is his covering letter like? Does his covering letter (and CV) demonstrate he has the necessary professional competencies (remember HR as well as SATCOs will read these)? It needs to be carefully worded, with the best will in the world it would be difficult to sell you abilities if you have been based at one of our ‘less dynamic’ bases for years. Has he considered FTRS? There are a few about.
Remember most SATCOs know exactly what being a mil controller entails (either through personal experience or the experience of those that work for him/her), you can’t bull**** them.
I wish him luck.