RexBanner
To be fair, a lot of 787 pilots are flying almost full rosters. Can't speak for the 350.
However, the key here is training. With the new 787 deliveries, the training department allegedly was unable to deliver enough courses to get enough pilots on line to cover this. So the idea of then chopping further 787 pilots would be nothing but damaging to the business.
I can't argue a case for the, albeit tiny, number of pilots yet to complete training. However, I'd guess its just for legal simplicity.