Hi Glenn,
If you have a signal coming into AAM with this data, it should be possible using less than / greater than operations in a trait.
https://docs.adobe.com/content/help/en/audience-manager/user-guide/features/traits/trait-builder/tra...
I would look into the data your sending AAM, and if possible capture the current time in 24 hour format, and send in on a specific evar or prop.
For example evar55 (random number) could contain all the value of the 24 hour times: 1100, 1345, 1400, etc.
Your trait would be (evar55 <= '1400' AND evar55 >= 1100).
This only really solves half the question.. once the user has this trait on their profile, there is no way to exclude the user, unless you had other traits set to capture the time outside that 11-2 window, and used that trait in a AND NOT segment rule. To drop out of the segment for the media pool the next day, set both traits to use a TTL of 1 day or segment rule recency of <= 1.