Not speaking for the OP, but I think you have a pretty narrow view, IMHO.is their a reason you definitely want the R-ATP route ? The final place he wants to go is going to require ATP. And he will have some hourly benefits, but age will rule him out. And between 17-22 years - its a lot of time to just be eligible to get the full ATP. I ask because many places require ATP anyhow, and your options for being hired early with an R-ATP are kind of limited. So is it really worth it ? But this also assumes that you are willing to explore the non-141 R-ATP options that are available - notably a much cheaper option going through part 61 vs 141. but that option doesnt allow unrestricted loans. If college is something you want - get a 4 year degree - be a student - learn/educate and continue to work and get your ratings through the 4 years. Hell, I know college students who are CFI's at nearby airports (not affiliated with the university). But get a "real" degree from a college.
Now if college isnt for you - totally get it. You're just using the college for loans to get your flight certs and end up with a lower grade ATP (for awhile) and a lower rate college degree - but you'll get it done together. Which is understandable. The only "college affiliated" flight school I would say doesnt qualify under not as good would be Purdue. But rumor is their flight school is a bit of a mess as well (as many are).
I've heard good things about Purdue. Don't know your source. And Ohio State, Baylor, Auburn, and many other well regarded universities have approved R-ATP programs.
Of course, experience matters and pro pilot options are more limited at 21YO and 1001 hours than at 23YO and 1501 hours. But there are certainly more options with an R-ATP than with a COM rating.
The whole 141 vs 61 debate is interesting. I've always done part 61, but that worked for me. I absolutely see the value of a structured program though. And I'm not an airline pilot, but I do see the value of learning in a structured CRM model for that path.
College may or not be for everyone, but it has proven to be helpful for many.
The loan thing seems like a red herring. My kid wants the Airline Pilot route, no loans are in play.