大方廣圓覺修多羅了義經略疏 2.135

2.135

意顯此性定是新熏，非自本有，故云非眾生咎。前諸種性亦例此知，但文略也。則知眾生本同覺性，但遇教成差，有大有小、有邪有正，故知發心之者，切須善辨宗途。然餘經論目第五性云無性者，但明本來不覺，染心相續，未有邪正師教所熏，無三乘種故聞亦不信，由此濫於本有。今云外道性者，決了新熏之義彰矣。

The meaning is to reveal that this nature is definitely newly perfumed and not inherently possessed from the beginning; hence it says "not the fault of the sentient beings." The previous gotras are to be understood by analogy with this, the text being merely concise. Thus we know that sentient beings originally share the same enlightened nature; it is only upon meeting teachings that divergences arise, resulting in great and small, heterodox and correct. Hence we know that those who bring forth the mind must carefully discern the doctrinal path. However, when other sūtras and treatises designate the fifth nature as the "natureless," they merely explain that originally they are unawakened and their defiled mind continues uninterrupted; not having yet been perfumed by the teaching of heterodox or correct masters, they lack the seeds of the three vehicles, and so upon hearing they do not have faith either. Because of this, it was mistakenly conflated with being inherently possessed. Now calling it the "non-Buddhist nature," the meaning of newly perfumed is definitively illuminated and made clear.