The location rules are a nested set of arrays, this is your example with some comments
'location' => array (
// each array added at this lever has a relation of 'OR'
// in this case the location rules are
// post_type == portfolio OR post_type == team
array (
// each array at this nesting level has a relation of 'AND'
array (
'param' => 'post_type',
'operator' => '==',
'value' => 'portfolio',
),
// if this rule had an 'AND' it would appear here
),
// OR
array (
array (
'param' => 'post_type',
'operator' => '==',
'value' => 'team',
),
),
)
