Validation Placeholders being ignored for is_unique

Any updates on this? This comes in to play when post data needs validating and you call a validation rule set by name... instead of by array... so you can't actually pass {$id}:

$this->validate('user')

The is_unique rule does not check for post data... it only looks if the value was passed in the check.

Look at my example to see how I worked around this... but I'm not sure if there is a better way?