expand_checkboxes #default_value when #access=FALSE

several contrib modules fail to comply with FAPI #access property
when an element of #type=checkboxes has #access=FALSE

usually modules expect to receive data like:

array(
  7 => 7, // checked
  13 => 0, // unchecked
  21 => 21, // checked
)

but when a form is altered, and #access turned into FALSE, data comes like:

array(
  7 => 1, // checked
  13 => 0, // unchecked
  21 => 1, // checked
)

therefore, common code doing an array_filter and keeping the values (instead of the keys) use to fail,
instead they should prevent this by doing drupal_map_assoc(array_keys(array_filter($values))) [sigh]

the biggest problem being, that most modules work fine until they are required to play nicely with other 3rd party code altering #access rules
therefore, security alterations use to introduce bugs, instead of the intended FAPI Access Control

where does this come from?
function expand_checkboxes doing '#default_value' => isset($value[$key]),

as you will notice, this was already fixed in D7 counterpart
function form_process_checkboxes by means of '#default_value' => isset($value[$key]) ? $key : NULL,
bringing sanity back to those checkboxes with #access=FALSE which will enter form_type_checkbox_value with $edit being FALSE and end up returning the #default_value