The marshal format used by pyc files is explicitly documented[1] to be unsafe, just a fast way to cache the compiled byte code to a .pyc file next to the .py source file. The Python VM is not a sandbox so there has been no need for an untrusted bytecode format.
That's true, but looking at crashes, the 'exploitable' marks some of them as exploitable, there are also heap errors. Might be an easy entry point to do... something ;)
We did similar excercise a year ago with zpaq, and Matt and community was able to fix it so well that now you can fuzz it pretty much forever :)
[1] see big red warning box at https://docs.python.org/3/library/marshal.html