I'd reply: How would such a requirement after being vetted and agreed upon ever get passed to a developer?  A request is not a requirement ... the issue is not 'how?' (that's easy join the keys where the granularity matches) - but the 'why?' (the rules of dimensional modeling are thrown out)

YOU are interviewing them too ... do you really want to do development work for people who would disregard the rules of modeling to have you implement/develop things in a tool that is based on those very same rules?  "Go where you will be celebrated" - is often a moniker of HR and recruiting -- apply it to you.  Celebration of your skill implies adherence to the common knowledge base you and they share (namely: dimensional modeling).

Hth,I would appreciate if you mark our answers as such! :-)