System flush enables jobs disabled through scheduled jobs

When I define a scheduled_job in an extension .mgd file I deliberately don't set it to enabled, intending people to be able to enable or disabled. But, every time something causes 'system.flush' the jobs are re-enabled. is_active is the default for the api I guess - but it's not in the spec I defined

array (
'name' => 'CiviXero Invoice Pull Job',
'entity' => 'Job',
'params' =>
array (
'version' => 3,
'name' => 'CiviXero Invoice Pull Job',
'description' => 'Pull updated invoices from Xero',
'api_entity' => 'Civixero',
'api_action' => 'invoicepull',
'run_frequency' => 'Always',
'parameters' => 'plugin=xero, start_date=yesterday',
),
),
);