$self->{Person} = \shift; in Updater->new should be    $self->{Person} = shift;. The Person object is already a reference. Given that change the following code:

package main;

my $him = Person->new ('Bob wibble');
my $ud = Updater->new ($him);

$ud->updateName ();
print $ud->{NAME};
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prints:

Bob wibble
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