Isn't TM1 in(PC)memory? the main HANA's benefit is that aggregations happen on the database server and only the results are returned to a BI (for me it's Excel) client. why would you like to copy detail into TM1 (not sure if it's doable) and not create a bunch of HANA calculation views and expose them through ODBO into the spreadsheet pivot table?
i don't think TM1 folks care that much about HANA, but then again spreadsheet users don't necessarily care about TM1.
just an architectural thought or two...