Looking at the source for CGI::autoEscape shows this:

#### Method: autoescape
# If you want to turn off the autoescaping features,
# call this method with undef as the argument
'autoEscape' => <<'END_OF_FUNC',
sub autoEscape {
    my($self,$escape) = self_or_default(@_);
    my $d = $self->{'escape'};
    $self->{'escape'} = $escape;
    $d;
}
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Basically, the accessor always mutates the value. So I'd suggest just treating it like a mutator only.