The file is not really random, though, since Mike generated it and had time to make sure it was a "good" file before sending it on.

That is, if the file was truly random, it would have a chance of 1/(2^X) of being all 0, where X is the size of the file. But since Mike would reject that file, the chance is actually 0.

Same for all files with easily exploitable patterns - for example, I am sure that Goldman checked that the file could not be compressed with gzip before sending it.

So the EV is probably not positive, even if there is a small chance that a random file of size X can be compressed.