If you mean your friend will miss a private transfer that (I'll hazard a guess) you have booked from LYS to a ski resort, then no, BA is only responsible for getting them to LYS, and onward travel will be a matter for insurance.

But as already mentioned BA is responsible for statutory compensation if the delay is long enough, and also for 'duty of care' while they are waiting - so basically food and drink, within reason.