Well, Section Access isn't applied when distributing reports. To do this, you would need to create a table of users (DOMAIN\USERNAME or USERNAME@DOMAIN) in your data model (linked properly in a way that shows permissions) and then modify your report so it bands over this username field. You would then need to do a loop-and-distribute in Publisher so that it uses this same user field, or a field related to it in the same table, as the recipient of this report. This is actually a fairly complicated process, but check out the Server Reference Manual.
Regards,
Vlad
