Your use case would be :
$ArrayCollectionOfActiveUsers = $customer->users->filter(function($user) {
return $user->getActive() === TRUE;
});
if you add ->first() you'll get only the first entry returned, which is not what you want.
@ Sjwdavies You need to put () around the variable you pass to USE. You can also shorten as in_array return's a boolean already:
$member->getComments()->filter( function($entry) use ($idsToFilter) {
return in_array($entry->getId(), $idsToFilter);
});