Suppressing the Notification

Disable all the Carriers at once

This is the best approach if you have to test the specific Notification, instead of a single Carrier.

To do this, you should use the filter:

add_filter(
    'notification/should_send',
    function($shouldSend, $notification, $trigger) {
        if ($something) {
            $should_send = false;
        }

        return $should_send;
    },
    10,
    3
);    

At this point, the Trigger doesn't execute the context() method so you cannot use the Merge Tags. If you rely on Merge Tags, suppress the Carrier instead.