Top 5 “Destination” airlines require a degree, one or two may make an exception if you have a really strong military flying background.
Such as flying transports or tankers across the oceans for a good number of years.
So two options:
1. A good flight school can do zero to instructor in about 6-9 months with full time training.
Then go off to college for a degree in something remotely useful in case of loss of medical somewhere down the line.
Work your way through college with flight instruction on the side and he might well have 1000-1200hrs by then.
This will likely be the less expensive option.
2. Go to a University that has a strong aviation department and do all your ratings there while getting a degree. You’ll flight instruct the last 2-2.5 years.
Advantage would be you could do your Restricted ATP at 1200 hrs.
https://www.faa.gov/pilots/training/...ority_List.pdf
In case he’s sick of school and doesn’t want to further his education:
It takes about 3 years to get from zero - 1500hrs for your ATP.
Thats 3/4 the way through a degree.
GET A DEGREE!