Mistaking froth for brains is humanity's oldest problem.
I agree. In the case of CF, more trivially, it was mistaken froth for liquids, probably.
As for why, it's because the dead can't fight back.
Is this the reason why humanity does not adopt the Ptolemy's model anymore?
Anyway, SP can still explain his point of view on the foam issue, and he probably is the more entitled to do that: