I think that there are many ways how to achieve desired effect. Using EM is probably not reason for excess heat, It is only way, how you can achieve particular thing that is required later.
You can use even one heater for multiple purposes at the same time. You can use it for heating only, but also as induction heater later.
Rossi is in the state, that he know limitation of each part and he want to sell reliable product. So one thing is to make it work, second to make it durable.
So even there are many ways to get excess heat, you have to find the best one.
I think that he is fighting with some mechanical limitations even now.