This seems to be more a concern on the terms rather than the instrument. You can structure any financial instrument (ISA, loan, whatever) to be predatory if you're willing to play with the variables sufficiently.

I don't know if those are real terms in your example, but they do seem pretty bad. (Although still better than a predatory loan IMO, since they are contingent on the student actually having a somewhat successful outcome).

By contrast, something like Lambda's ISA ($30k max payment vs $20k upfront tuition; 15% of income for two years; min $50k/y salary as software engineer) strikes me as not predatory in any way -- I would guess they make less money from their ISA students on average than from their tuition-paying students.