What happens to my Business Rewards Miles if my Emirates flight gets cancelled or disrupted and I am transferred to another airline?

You will earn Business Rewards Miles as per the original booking on your ticket if the cancellation/disruption was due to operational reasons.

Related questions

Can I earn Business Rewards Miles on any Emirates or Emirates Skywards partner airlines or codeshare flights?
Can I earn Business Rewards Miles on flights taken before I joined Business Rewards?
For how long are Business Reward Miles valid?