Actually, hiding channels is very similar to creating favorite lists as far as the receiver is concerned. The receiver accepts the guide update package, processes it and then decides what to display(or not) in various categories based on your lock, hide, favourite, etc. selections.
Because communication is one-way, you can not tell the satellite not to send data for specific channels. Nor will the receiver reject or delete data based on locked out or hidden channels. If you lock out or hide a channel and then restore it, you will see that the data is still there.