Just to be clear, reading the other thread for context, your flights were cancelled and BA has refunded them while you wish other accommodation under Sec. 8 (rebooking rights) of EC 261/2004.

But, the European Commission has issued Guidance in April making it clear that under the circumstances of the pandemic, offering only a refund is acceptable. The force majeure term seems a bit silly, but in reading the Guidance, without using that term, it describes such a situation. So, not likely meaningful.