Will think about it and get back to it here, with (initially probably wrong) examples, as the first line in the settings seems clear, the second has a few options, they pose the questions.
Actually no, it won't work like so.
The customer will be able to send 1k emails in one hour and then that's all, nothing else.
If you want him to be able to send 1000k per hour, then next hour another 1000 and so on, best is to assign him a delivery server with that sending quota. otherwise, if you prefer customer groups (though they were not meant for such usage) you have to set a proper "Action when quota reached" in this case, to reset the counters for a fresh start.