There is also nothing on the _status attribute to prevent something accessing it directly and setting it to an invalid value

That shouldn't be a consideration because you'll never be able to prevent someone from going around the normal process. For example, 

$obj->{'_status'} = 'junk';

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In reply to Re: Moose: mutualy exclusive bolean attributes. by ikegami
in thread Moose: mutualy exclusive bolean attributes. by chrestomanci

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