To be expected
CakePHP only returns what the underlying driver returns, as such it is Db-dependent, but if you're observing all values are strings then yes, it should be that way.
For example, using the mysql driver results are always returned as strings:
<?php
mysql_connect("localhost", "user", "pass");
$resource = mysql_query("select * from cakephp.posts");
$myrow = mysql_fetch_row($resource);
var_dump($myrow);
Results in:
array(5) {
[0] => string(1) "1" # <- autoincrement int primary key value
[1] => string(9) "The title"
[2] => string(22) "This is the post body."
[3] => string(19) "2013-08-01 07:34:57"
[4] => string(19) "2013-08-01 07:34:57"
}