Argument C affirms that argument B (for the duty to say
that Bob is away) is stronger than argument A (for the duty not
to make that statement). Therefore, we can conclude that the defeat link
from B to A is OUT (as a weaker argument cannot rebut a
stronger one), while the defeat link from A to B remains
IN. Therefore, B strictly defeats A (it defeats it without
being defeated by it). Consequently, B is IN and A is OUT:
we should tell the lie.
Obviously, the opposite conclusion would follow if we took a different
view of priorities, such as the view that deontological arguments,
warranted by generalizable rules, always have priority over
consequentialist arguments.