One thing to bear in mind is that many people travelling from Europe to Australia don't actually stop over for a few days, so it doesn't make much difference where they change planes.
They 'don't like the cut of your jib'. They probably don't even need to give a reason.
I remember talking on this subject 15+ years ago with an old friend. As he said, if the IO flicks through your passport and finds ovestays almost on every other page (I had another old friend who was the overstay-king!), he might take a dim view. Also if you've submitted the passport to aThai embassy for a visa. And this was in the days before time spent in Thailand really became an issue.
I probably have 2 or 3 overstay stamps over a 20 year period.
Even with a visa, entry to Thailand isn't guaranteed, the final decision is up to the IO.
I doubt that this guy will have a problem with one short overstay though.
Having done this myself I would advise making sure you have $US for the Laos visa fee, if you pay in Baht you get a really bad exchange rate, I think it was about $3 to the bad the last time I did it at Non Khai.
(I know many less well-off expats are counting the pennies).
Many of my British compatriots have it in their heads that our country is still a major-league world power, when in fact we're a mid-sized (second-tier) power, similar to France.
I actually go to work an hour or so early every day and do 20-30 minutes walking around the supermarket car park to get some exercise. My job actually involves driving, 90% of it, so I have to get some exercise.
I'm only 57. Occasionally I visit my mother's grave. Not too far away are the plots where children, many of them very young are buried. I think to myself how increbibly lucky we have been to reach the age that we have.
Just because he's a regular jogger doesn't necessarily mean he's healthy. He could be a borderline alcoholic, and a smoker, unhealthy diet, for most of his life, and still manage to go for a jog.