We have helped DS buy a flat with a substantial interest free loan (about 45% of the purchase) rest from inheritance from DM. He is now saying he must have a freehold property and is planning to move 100+ miles from his work and commute in as he is in office only 2 days of 5 as he can't afford a freehold anywhere nearer. He lives with gf who is long term sick, unsure how much she contributes financially as they won't discuss it with us.
I feel a flat is fine just for the two of them. Would consider upping the loan ( we can't give the extra money outright or would have to do the same for his brother, also there's imo a risk that he could be financially exploited) so he could get a two bed flat nearer in but he insists it's freehold or nothing.
For context he is autistic, finally (took a few years) in regular work but not that well paid. He meets all expenses but obviously is rent free which in the SE would be a significant dent. We want him to have a predictable and secure home but feel this is unrealistic and will cost him far, far more in fares and increased running costs than he saves in service charges. He appears to assume freehold is always best, end of story.
How can I word this so as to get it factual and non-accusatory? Any impediment to or questioning of his plans usually results in a strop and doubling down on original intentions.
Or do we need to accept his plans and let him find out on his own?