They are not doing anything wrong so I'm not sure why anyone is "accusing" them of something.
I've read this post, what they do is clear and makes sense to me.
Most of all it preservers "if the student doesn't get the job, LambdaSchool fails" property. This alignment of incentives is really the only thing that matters and it lacks in traditional colleges (which is why Lamda will either fail or, in the long term, will kill traditional colleges or force them to change).
Comparing what they do to CDO is done to make a negative association. "CDO are bad, this shares some similarity of CDO, this is bad".
The bad aspect of CDO was that it was used to hide bad investments by packaging them together and re-selling as a better investment.
What Lambda is doing is more like pooling of risk used in insurance: if you (as an investor) bet on ISA of a single student, you have a high-risk, binary outcome (loose all your money or get some reward).
If you bet on 1000 students as a group, you significantly de-risk the whole thing while only reducing potential reward a little bit.