成唯識論演祕 2.33

2.33

非色喻言攝無為等，無為無礙，不成衣等，故入同中，故彼不得將為不定。

The phrase 'non-material example' subsumes the unconditioned and so forth; the unconditioned is unobstructed and does not form cloth and the like, so it enters into the positive [example]; therefore, they cannot take it as inconclusive.