How is it catch 22? Banks do the exact same thing for people buying a house. You might be able to afford the repayments on a house but they want a bigger deposit or renegotiate terms to limit the risk.
As I said in my post the banks will only release the funds when the amount they are willing to loan the club directly equals or greater than the amount to finish the stadium. That obviously hasn't gotten to that point yet.
The stadium in an unfinished state is by far the biggest risk to bank, if it's not complete it doesn't generate any revenue so their avenue to get back the hundreds of millions loaned out is pretty slim. Do they then have to stump up cash to finish it to then sell? So to say this is a bit of a mistake:
I think it's very much in their interest that the funds essentially guarantee the build's completion.
It's no good pointing at other builds as they are not comparable, Arsenal's stadium costs were nowhere near as large and a lot of that could be paid back by redevelopment of Highbury. A large portion of Spurs' loans have been probably underwritten by their owner, the exact same method that you've derided but isn't now an option due to Usmanov's persona non grata status.