Emily writes:

He didn't hear ANYTHING but a heterodyne.

Not so. The transmission was hard to make out, but it was not
completely obliterated.

And even if he had heard only that, a squeal is not a take-off
clearance. Either he was deliberately negligent, or he heard
something he wanted to hear.

The actual situation was more complex, but misunderstanding was a key
part of it.

If you want to say he heard
the heterodyne as clearance to take off, fine, but that's not what we're
talking about.

That counts as hearing what you want to hear.

The OP stated that AM results in poor transmission quality and
therefore pilots will hear what they want to hear.

Yes. When a transmission is ambiguous, pilots will hear what they
want to hear.

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