The kid is taking the basic Direct loans which amounts to $31k over 4 years, plus interest. I’m assuming some of this is subsidized. That is usual these days.
The OP will take out and be involved in repaying the additional $40-$50k snd has finds in a 529 to do so. The issue here is to maximize financial aid, so taking money directly out of 529 as noncustodial parent is not a good idea if alternatives can be found. OP can use 529 to repay $10k of loans he takes out, and student can do the same. But for the first years, any 529 disbursements could drastically reduce Financial aid.
The parent is looking for a way to temporarily borrow the money. Not sticking it to the kid to take out $80k in loans that kid has to repay.