I will climb FL 350 because 25000 it's only if you have had the failure on the ground.
the MEL anticipate the failure of the second bleed or pack
it's just in case of
in flight also you read the MEL it gives you information and helps you to take your decision.
and this it's also true for an other aircraft like MD80.
We had the same limitations.
in flight you have just to follow the QRH instruction.