Tell them to double check in Cisco Commerce Workspace (CCW). While the Ordering Guide and base SKUs indicate 1-, 3- and 5-year terms, you can override the defaults and select a lesser (or greater - not to exceed the next tier) term. For instance, the actual term for a 1-year SKU can be customized to a range from 1-35 months. You can also specify the start and end date to make them co-term.
I was a Cisco customer for over 20 years before going to the partner side. I know some partners can be either uninformed or uncooperative about the more advanced requests. If you run into this, escalate it until you get somebody more helpful or reach out to your Cisco Account Manager to express your frustration. Most will do whatever is in their power to address a customer satisfaction issue.
I just built a validated configuration for an ASA 5506 with FTD and specified a 9 month license term.
You can see snippets from it as follows:

