Since you are the author of TPP could you please explain how your example shows some sort of quadratic parsing DOS? I don't see anything like that. Just a huge number of signatures.
The postmortem on that DoS attack was at pains to point out that they were "officially" documenting only one of the vulnerabilities. Somewhere on an old drive I have the giant mountain of mailing list posts I sorted through to write that post, and I may dig it out at some point, but right now you're just going to have to take my word for the fact that I was not suggesting that the only problem with the packet format was the fact that you can represent lengths 8 different ways.
This is a deeply silly discussion to be having on this particular thread, which, again, is about a vulnerability that owes to the PGP packet format.